def encrypt(seed, passphrase): """ Encrypt the Electrum seed """ #1. Decode the seed value to the original number seed = mn_decode(seed.split()) #2. Take a hash of the decoded seed to act as a scrypt salt salt = hashlib.sha256(hashlib.sha256(seed).digest()).digest()[:4] #3. Derive a key from the passphrase using scrypt key = scrypt.hash(passphrase, salt, 16384, 8, 8) #4. Split the key into half 1 and half 2 derivedhalf1 = key[0:32] derivedhalf2 = key[32:64] #5. Do AES256Encrypt(seedhalf1 xor derivedhalf1[0...15], derivedhalf2), call the 16-byte result encryptedhalf1 # (Electrum may change the number of words in a seed so we should future proof by just using the halfs rather than hardcoded lengths) Aes = aes.Aes(derivedhalf2) encryptedhalf1 = Aes.enc(enc.sxor(seed[:int(math.floor(len(seed)/2))], derivedhalf1[:16])) #6. Do AES256Encrypt(seedhalf2 xor derivedhalf1[16...31], derivedhalf2), call the 16-byte result encryptedhalf2 encryptedhalf2 = Aes.enc(enc.sxor(seed[int(math.floor(len(seed)/2)):len(seed)], derivedhalf1[16:32])) #7. The encrypted private key is the Base58Check-encoded concatenation of the following # \x4E\xE3\x13\x35 + salt + encryptedhalf1 + encryptedhalf2 # (\x4E\xE3\x13\x35) gives the 'SeedE' prefix) encSeed = '\x4E\xE3\x13\x35' + salt + encryptedhalf1 + encryptedhalf2 check = hashlib.sha256(hashlib.sha256(encSeed).digest()).digest()[:4] return enc.b58encode(encSeed + check)
def encrypt(pub_address, passphrase): """ Encrypt the public address """ #1 base 58 decode the public address address = enc.b58decode(pub_address) #2. Take a hash of the decoded address to act as a scrypt salt salt = hashlib.sha256(hashlib.sha256(address).digest()).digest()[:4] #2. Derive a key from the passphrase using scrypt key = scrypt.hash(passphrase, salt, 16384, 8, 8) #3. Split the key into half 1 and half 2 derivedhalf1 = key[0:32] derivedhalf2 = key[32:64] #4 AES encrypt address halves as per bip38 halflength = int(math.floor(len(address) / 2)) Aes = aes.Aes(derivedhalf2) #for Aes encryption, string needs to have length = 16 xorhalf1 = enc.sxor(address[:halflength], derivedhalf1[:16]).ljust(16, '0') xorhalf2 = enc.sxor(address[halflength:], derivedhalf1[16:32]).ljust(16, '0') encryptedhalf1 = Aes.enc(xorhalf1) encryptedhalf2 = Aes.enc(xorhalf2) #5. The encrypted private key is the Base58Check-encoded concatenation of the following # \x78\x8e\xa3\x69\xb6 + address_length + salt + encryptedhalf1 + encryptedhalf2 encAddress = '\x78\x8e\xa3\x69\xb6' + chr(len(address)) + salt + encryptedhalf1 + encryptedhalf2 check = hashlib.sha256(hashlib.sha256(encAddress).digest()).digest()[:4] return enc.b58encode(encAddress + check)
def encrypt(privK, Baddress, Saddress, passphrase):
"""
BIP0038 private key encryption, Non-EC
"""
# 1. take the first four bytes of SHA256(SHA256(address)) of it. Let's call this "addresshash".
addresshash = hashlib.sha256(hashlib.sha256(Baddress + Saddress).digest()).digest()[:4]
#2. Derive a key from the passphrase using scrypt
# a. Parameters: passphrase is the passphrase itself encoded in UTF-8.
# addresshash came from the earlier step, n=16384, r=8, p=8, length=64
# (n, r, p are provisional and subject to consensus)
key = scrypt.hash(passphrase, addresshash, 16384, 8, 8)
#Let's split the resulting 64 bytes in half, and call them derivedhalf1 and derivedhalf2.
derivedhalf1 = key[0:32]
derivedhalf2 = key[32:64]
#3. Do AES256Encrypt(bitcoinprivkey[0...15] xor derivedhalf1[0...15], derivedhalf2), call the 16-byte result encryptedhalf1
Aes = aes.Aes(derivedhalf2)
encryptedhalf1 = Aes.enc(enc.sxor(privK[:16], derivedhalf1[:16]))
#4. Do AES256Encrypt(bitcoinprivkey[16...31] xor derivedhalf1[16...31], derivedhalf2), call the 16-byte result encryptedhalf2
encryptedhalf2 = Aes.enc(enc.sxor(privK[16:32], derivedhalf1[16:32]))
#5. The encrypted private key is the Base58Check-encoded concatenation of the following, which totals 39 bytes without Base58 checksum:
# 0x01 0x42 + flagbyte + salt + encryptedhalf1 + encryptedhalf2
flagbyte = chr(0b11100000) # 11 no-ec 1 compressed-pub 00 future 0 ec only 00 future
privkey = ('\x01\x42' + flagbyte + addresshash + encryptedhalf1 + encryptedhalf2)
check = hashlib.sha256(hashlib.sha256(privkey).digest()).digest()[:4]
return enc.b58encode(privkey + check)
def confirmationcode(flagbyte, addresshash, ownerentropy, factorb, derivedhalf1, derivedhalf2):
"""
The party generating the Bitcoin address has the option to return a confirmation code back to owner which allows owner
to independently verify that he has been given a Bitcoin address that actually depends on his passphrase,
and to confirm the lot and sequence numbers (if applicable).
This protects owner from being given a Bitcoin address by the second party that is unrelated to the key derivation and possibly spendable by the second party.
If a Bitcoin address given to owner can be successfully regenerated through the confirmation process,
owner can be reasonably assured that any spending without the passphrase is infeasible.
This confirmation code is 75 characters starting with "cfrm38".
To generate it, we need flagbyte, addresshash, ownerentropy, factorb, derivedhalf1 and derivedhalf2 from the original encryption operation.
"""
#1. ECMultiply factorb by G, call the result pointb. The result is 33 bytes (compressed key format).
pub = elip.base10_multiply(elip.G, enc.decode(factorb, 256))
pointb = ('0' + str(2 + (pub[1] % 2)) + enc.encode(pub[0], 16, 64))[:33]
#2. The first byte is 0x02 or 0x03. XOR it by (derivedhalf2[31] & 0x01), call the resulting byte pointbprefix.
pointbprefix = enc.sxor(pointb[:1], str(derivedhalf2[31]) + '\x01')
#3. Do AES256Encrypt(pointb[1...16] xor derivedhalf1[0...15], derivedhalf2) and call the result pointbx1.
Aes = aes.Aes(derivedhalf2)
pointbx1 = Aes.enc(enc.sxor(pointb[1:17], derivedhalf1[0:16]))
#4. Do AES256Encrypt(pointb[17...32] xor derivedhalf1[16...31], derivedhalf2) and call the result pointbx2.
pointbx2 = Aes.enc(enc.sxor(pointb[17:33], derivedhalf1[16:32]))
#5. Concatenate pointbprefix + pointbx1 + pointbx2 (total 33 bytes) and call the result encryptedpointb.
encryptedpointb = pointbprefix + pointbx1 + pointbx2
#6. The result is a Base58Check-encoded concatenation of the following:
#0x64 0x3B 0xF6 0xA8 0x9A + flagbyte + addresshash + ownerentropy + encryptedpointb
inp_fmtd = '\x64\x3B\xF6\xA8\x9A' + flagbyte + addresshash + ownerentropy + encryptedpointb
check = hashlib.sha256(hashlib.sha256(inp_fmtd).digest()).digest()[:4]
return enc.b58encode(inp_fmtd + check)
def confirmationcode(flagbyte, addresshash, ownerentropy, factorb,
derivedhalf1, derivedhalf2):
"""
The party generating the Bitcoin address has the option to return a confirmation code back to owner which allows owner
to independently verify that he has been given a Bitcoin address that actually depends on his passphrase,
and to confirm the lot and sequence numbers (if applicable).
This protects owner from being given a Bitcoin address by the second party that is unrelated to the key derivation and possibly spendable by the second party.
If a Bitcoin address given to owner can be successfully regenerated through the confirmation process,
owner can be reasonably assured that any spending without the passphrase is infeasible.
This confirmation code is 75 characters starting with "cfrm38".
To generate it, we need flagbyte, addresshash, ownerentropy, factorb, derivedhalf1 and derivedhalf2 from the original encryption operation.
"""
#1. ECMultiply factorb by G, call the result pointb. The result is 33 bytes (compressed key format).
pub = elip.base10_multiply(elip.G, enc.decode(factorb, 256))
pointb = ('0' + str(2 + (pub[1] % 2)) + enc.encode(pub[0], 16, 64))[:33]
#2. The first byte is 0x02 or 0x03. XOR it by (derivedhalf2[31] & 0x01), call the resulting byte pointbprefix.
pointbprefix = enc.sxor(pointb[:1], str(derivedhalf2[31]) + '\x01')
#3. Do AES256Encrypt(pointb[1...16] xor derivedhalf1[0...15], derivedhalf2) and call the result pointbx1.
Aes = aes.Aes(derivedhalf2)
pointbx1 = Aes.enc(enc.sxor(pointb[1:17], derivedhalf1[0:16]))
#4. Do AES256Encrypt(pointb[17...32] xor derivedhalf1[16...31], derivedhalf2) and call the result pointbx2.
pointbx2 = Aes.enc(enc.sxor(pointb[17:33], derivedhalf1[16:32]))
#5. Concatenate pointbprefix + pointbx1 + pointbx2 (total 33 bytes) and call the result encryptedpointb.
encryptedpointb = pointbprefix + pointbx1 + pointbx2
#6. The result is a Base58Check-encoded concatenation of the following:
#0x64 0x3B 0xF6 0xA8 0x9A + flagbyte + addresshash + ownerentropy + encryptedpointb
inp_fmtd = '\x64\x3B\xF6\xA8\x9A' + flagbyte + addresshash + ownerentropy + encryptedpointb
check = hashlib.sha256(hashlib.sha256(inp_fmtd).digest()).digest()[:4]
return enc.b58encode(inp_fmtd + check)
def encrypt(pub_address, passphrase):
"""
Encrypt the public address
"""
#1 base 58 decode the public address
address = enc.b58decode(pub_address)
#2. Take a hash of the decoded address to act as a scrypt salt
salt = hashlib.sha256(hashlib.sha256(address).digest()).digest()[:4]
#2. Derive a key from the passphrase using scrypt
key = scrypt.hash(passphrase, salt, 16384, 8, 8)
#3. Split the key into half 1 and half 2
derivedhalf1 = key[0:32]
derivedhalf2 = key[32:64]
#4 AES encrypt address halves as per bip38
halflength = int(math.floor(len(address) / 2))
Aes = aes.Aes(derivedhalf2)
#for Aes encryption, string needs to have length = 16
xorhalf1 = enc.sxor(address[:halflength], derivedhalf1[:16]).ljust(16, '0')
xorhalf2 = enc.sxor(address[halflength:],
derivedhalf1[16:32]).ljust(16, '0')
encryptedhalf1 = Aes.enc(xorhalf1)
encryptedhalf2 = Aes.enc(xorhalf2)
#5. The encrypted private key is the Base58Check-encoded concatenation of the following
# \x78\x8e\xa3\x69\xb6 + address_length + salt + encryptedhalf1 + encryptedhalf2
encAddress = '\x78\x8e\xa3\x69\xb6' + chr(
len(address)) + salt + encryptedhalf1 + encryptedhalf2
check = hashlib.sha256(hashlib.sha256(encAddress).digest()).digest()[:4]
return enc.b58encode(encAddress + check)
def intermediate2privK(intermediate_passphrase_string):
"""
Steps to create new encrypted private keys given intermediate_passphrase_string from owner
(so we have ownerentropy, and passpoint, but we do not have passfactor or the passphrase):
"""
#get ownerentropy and passpoint from the intermediate key
leadingzbytes = len(re.match('^1*',intermediate_passphrase_string).group(0))
data = '\x00' * leadingzbytes + enc.encode(enc.decode(intermediate_passphrase_string,58),256)
assert hashlib.sha256(hashlib.sha256(data[:-4]).digest()).digest().encode('hex')[:4] == data[-4:]
decodedstring = data[1:-4]
ownerentropy = decodedstring[7:15]
passpoint = decodedstring[-33:]
#1. Set flagbyte.
#Turn on bit 0x20 if the Bitcoin address will be formed by hashing the compressed public key (optional, saves space, but many Bitcoin implementations aren't compatible with it)
#Turn on bit 0x04 if ownerentropy contains a value for lotsequence.
#(While it has no effect on the keypair generation process, the decryption process needs this flag to know how to process ownerentropy)
flagbyte = chr(0b00100100) # 00 EC 1 compressed 00 future 1 has lotsequence 00 future
#2. Generate 24 random bytes, call this seedb. Take SHA256(SHA256(seedb)) to yield 32 bytes, call this factorb.
seedb = os.urandom(24)
factorb = hashlib.sha256(hashlib.sha256(seedb).digest()).digest()
#3. ECMultiply passpoint by factorb.
pub = elip.base10_multiply(enc.decode(factorb, 256), enc.decode(passpoint, 256))
#4. Use the resulting EC point as a public key and hash it into a Bitcoin address using either compressed or uncompressed public key methodology
# (specify which methodology is used inside flagbyte).
# This is the generated Bitcoin address, call it generatedaddress.
publicKey = ('0' + str(2 + (pub[1] % 2)) + enc.encode(pub[0], 16, 64))
generatedaddress = address.publicKey2Address(publicKey) ## Remember to add in the currency details here
#5. Take the first four bytes of SHA256(SHA256(generatedaddress)) and call it addresshash.
addresshash = hashlib.sha256(hashlib.sha256(generatedaddress).digest()).digest()[:4]
#6. Now we will encrypt seedb. Derive a second key from passpoint using scrypt
#Parameters: passphrase is passpoint provided from the first party (expressed in binary as 33 bytes).
# salt is addresshash + ownerentropy, n=1024, r=1, p=1, length=64. The "+" operator is concatenation.
encseedb = scrypt.hash(passpoint, addresshash + ownerentropy, 1024, 1, 1, 64)
#7. Split the result into two 32-byte halves and call them derivedhalf1 and derivedhalf2.
derivedhalf1 = encseedb[0:32]
derivedhalf2 = encseedb[32:64]
#8. Do AES256Encrypt(seedb[0...15] xor derivedhalf1[0...15], derivedhalf2), call the 16-byte result encryptedpart1
Aes = aes.Aes(derivedhalf2)
encryptedpart1 = Aes.enc(enc.sxor(seedb[:16], derivedhalf1[:16]))
#9. Do AES256Encrypt((encryptedpart1[8...15] + seedb[16...23]) xor derivedhalf1[16...31], derivedhalf2), call the 16-byte result encryptedpart2.
# The "+" operator is concatenation.
encryptedpart2 = Aes.enc(enc.sxor(encryptedpart1[8:16] + seedb[16:24], derivedhalf1[16:32]))
#10. The encrypted private key is the Base58Check-encoded concatenation of the following, which totals 39 bytes without Base58 checksum:
#0x01 0x43 + flagbyte + addresshash + ownerentropy + encryptedpart1[0...7] + encryptedpart2
inp_fmtd = '\x01\x43' + flagbyte + addresshash + ownerentropy + encryptedpart1[0:8] + encryptedpart2
check = hashlib.sha256(hashlib.sha256(inp_fmtd).digest()).digest()[:4]
BIPKey = enc.b58encode(inp_fmtd + check)
cnfrmcode = confirmationcode(flagbyte, addresshash, ownerentropy, factorb, derivedhalf1, derivedhalf2)
return BIPKey, generatedaddress, cnfrmcode
def intermediate(passphrase):
"""
Encrypting a private key with EC multiplication offers the ability for someone to generate encrypted keys knowing only an EC point derived from the original passphrase and
some salt generated by the passphrase's owner, and without knowing the passphrase itself.
Only the person who knows the original passphrase can decrypt the private key.
A code known as an intermediate code conveys the information needed to generate such a key without knowledge of the passphrase.
This methodology does not offer the ability to encrypt a known private key - this means that the process of creating encrypted keys is also the process of generating new addresses.
On the other hand, this serves a security benefit for someone possessing an address generated this way:
if the address can be recreated by decrypting its private key with a passphrase, and it's a strong passphrase one can be certain only he knows himself,
then he can safely conclude that nobody could know the private key to that address.
The person who knows the passphrase and who is the intended beneficiary of the private keys is called the owner.
He will generate one or more "intermediate codes", which are the first factor of a two-factor redemption system, and will give them to someone else we'll call printer,
who generates a key pair with an intermediate code can know the address and encrypted private key, but cannot decrypt the private key without the original passphrase.
An intermediate code should, but is not required to, embed a printable "lot" and "sequence" number for the benefit of the user.
The proposal forces these lot and sequence numbers to be included in any valid private keys generated from them.
An owner who has requested multiple private keys to be generated for him will be advised by applications to ensure that each private key has a unique lot and sequence number
consistent with the intermediate codes he generated.
These mainly help protect owner from potential mistakes and/or attacks that could be made by printer.
The "lot" and "sequence" number are combined into a single 32 bit number.
20 bits are used for the lot number and 12 bits are used for the sequence number,
such that the lot number can be any decimal number between 0 and 1048575, and the sequence number can be any decimal number between 0 and 4095.
For programs that generate batches of intermediate codes for an owner,
it is recommended that lot numbers be chosen at random within the range 100000-999999 and that sequence numbers are assigned starting with 1.
We are not using Lot Sequence and sequence so some changes are made to the instructions
"""
#1. Generate 8 random bytes, call them ownerentropy.
ownerentropy = os.urandom(8)
#4. Derive a key from the passphrase using scrypt
#Parameters: passphrase is the passphrase itself encoded in UTF-8. salt is ownersalt. n=16384, r=8, p=8, length=32.
#Call the resulting 32 bytes passfactor.
passfactor = scrypt.hash(passphrase, ownerentropy, 16384, 8, 8, 32)
#6. Compute the elliptic curve point G * passfactor, and convert the result to compressed notation (33 bytes). Call this passpoint.
#Compressed notation is used for this purpose regardless of whether the intent is to create Bitcoin addresses with or without compressed public keys.
pub = elip.base10_multiply(elip.G, enc.decode(passfactor, 256))
passpoint = ('0' + str(2 + (pub[1] % 2)) +
enc.encode(pub[0], 16, 64)).decode('hex')
#7. Convey ownerentropy and passpoint to the party generating the keys, along with a checksum to ensure integrity.
#The following Base58Check-encoded format is recommended for this purpose: magic bytes "2C E9 B3 E1 FF 39 E2 53" followed by ownerentropy, and then passpoint.
#The resulting string will start with the word "passphrase" due to the constant bytes,
#will be 72 characters in length, and encodes 49 bytes (8 bytes constant + 8 bytes ownerentropy + 33 bytes passpoint).
#The checksum is handled in the Base58Check encoding. The resulting string is called intermediate_passphrase_string.
input = '\x2C\xE9\xB3\xE1\xFF\x39\xE2\x53' + ownerentropy + passpoint
checksum = hashlib.sha256(hashlib.sha256(input).digest()).digest()[:4]
intermediate_passphrase_string = enc.b58encode(input + checksum)
return intermediate_passphrase_string
def intermediate(passphrase):
"""
Encrypting a private key with EC multiplication offers the ability for someone to generate encrypted keys knowing only an EC point derived from the original passphrase and
some salt generated by the passphrase's owner, and without knowing the passphrase itself.
Only the person who knows the original passphrase can decrypt the private key.
A code known as an intermediate code conveys the information needed to generate such a key without knowledge of the passphrase.
This methodology does not offer the ability to encrypt a known private key - this means that the process of creating encrypted keys is also the process of generating new addresses.
On the other hand, this serves a security benefit for someone possessing an address generated this way:
if the address can be recreated by decrypting its private key with a passphrase, and it's a strong passphrase one can be certain only he knows himself,
then he can safely conclude that nobody could know the private key to that address.
The person who knows the passphrase and who is the intended beneficiary of the private keys is called the owner.
He will generate one or more "intermediate codes", which are the first factor of a two-factor redemption system, and will give them to someone else we'll call printer,
who generates a key pair with an intermediate code can know the address and encrypted private key, but cannot decrypt the private key without the original passphrase.
An intermediate code should, but is not required to, embed a printable "lot" and "sequence" number for the benefit of the user.
The proposal forces these lot and sequence numbers to be included in any valid private keys generated from them.
An owner who has requested multiple private keys to be generated for him will be advised by applications to ensure that each private key has a unique lot and sequence number
consistent with the intermediate codes he generated.
These mainly help protect owner from potential mistakes and/or attacks that could be made by printer.
The "lot" and "sequence" number are combined into a single 32 bit number.
20 bits are used for the lot number and 12 bits are used for the sequence number,
such that the lot number can be any decimal number between 0 and 1048575, and the sequence number can be any decimal number between 0 and 4095.
For programs that generate batches of intermediate codes for an owner,
it is recommended that lot numbers be chosen at random within the range 100000-999999 and that sequence numbers are assigned starting with 1.
We are not using Lot Sequence and sequence so some changes are made to the instructions
"""
#1. Generate 8 random bytes, call them ownerentropy.
ownerentropy = os.urandom(8)
#4. Derive a key from the passphrase using scrypt
#Parameters: passphrase is the passphrase itself encoded in UTF-8. salt is ownersalt. n=16384, r=8, p=8, length=32.
#Call the resulting 32 bytes passfactor.
passfactor = scrypt.hash(passphrase, ownerentropy, 16384, 8, 8, 32)
#6. Compute the elliptic curve point G * passfactor, and convert the result to compressed notation (33 bytes). Call this passpoint.
#Compressed notation is used for this purpose regardless of whether the intent is to create Bitcoin addresses with or without compressed public keys.
pub = elip.base10_multiply(elip.G, enc.decode(passfactor, 256))
passpoint = ('0' + str(2 + (pub[1] % 2)) + enc.encode(pub[0], 16, 64)).decode('hex')
#7. Convey ownerentropy and passpoint to the party generating the keys, along with a checksum to ensure integrity.
#The following Base58Check-encoded format is recommended for this purpose: magic bytes "2C E9 B3 E1 FF 39 E2 53" followed by ownerentropy, and then passpoint.
#The resulting string will start with the word "passphrase" due to the constant bytes,
#will be 72 characters in length, and encodes 49 bytes (8 bytes constant + 8 bytes ownerentropy + 33 bytes passpoint).
#The checksum is handled in the Base58Check encoding. The resulting string is called intermediate_passphrase_string.
input = '\x2C\xE9\xB3\xE1\xFF\x39\xE2\x53' + ownerentropy + passpoint
checksum = hashlib.sha256(hashlib.sha256(input).digest()).digest()[:4]
intermediate_passphrase_string = enc.b58encode(input + checksum)
return intermediate_passphrase_string
def decrypt(enc_address, passphrase):
"""
Decrypt an Public Address encrypted with the above method
"""
#1. Base 58 decrypt the encrypted key
# get the two encrypted halves, the check and the salt
dec_address = enc.b58decode(enc_address)
check = dec_address[-4:]
#check that it's not been tampered with
if check != hashlib.sha256(hashlib.sha256(
dec_address[:-4]).digest()).digest()[:4]:
return False, 'checksum'
length = ord(dec_address[5:6])
halflength = int(math.floor(length / 2))
salt = dec_address[6:10]
encryptedhalfs = dec_address[10:len(dec_address) - 4]
encryptedhalf1 = encryptedhalfs[:16]
encryptedhalf2 = encryptedhalfs[16:]
#2. Derive the decryption key using scrypt
key = scrypt.hash(passphrase, salt, 16384, 8, 8)
derivedhalf1 = key[0:32]
derivedhalf2 = key[32:64]
#3. Aes decrypt the encrypted halves
Aes = aes.Aes(derivedhalf2)
xorhalf1 = Aes.dec(encryptedhalf1)
xorhalf2 = Aes.dec(encryptedhalf2)
#4 . xor them with the two halves of derivedhalf1 to get the original values
half1 = enc.sxor(xorhalf1[:halflength], derivedhalf1[:16])
half2 = enc.sxor(xorhalf2[:(length - halflength)], derivedhalf1[16:32])
#5. build the address and check it against the check hash
pub_address = half1 + half2
if salt != hashlib.sha256(
hashlib.sha256(pub_address).digest()).digest()[:4]:
return False, 'salt'
#6. return the address as a single string
return True, enc.b58encode(pub_address)
def decrypt(enc_address, passphrase): """ Decrypt an Public Address encrypted with the above method """ #1. Base 58 decrypt the encrypted key # get the two encrypted halves, the check and the salt dec_address = enc.b58decode(enc_address) check = dec_address[-4:] #check that it's not been tampered with if check != hashlib.sha256(hashlib.sha256(dec_address[:-4]).digest()).digest()[:4]: return False, 'checksum' length = ord(dec_address[5:6]) halflength = int(math.floor(length / 2)) salt = dec_address[6:10] encryptedhalfs = dec_address[10:len(dec_address) - 4] encryptedhalf1 = encryptedhalfs[:16] encryptedhalf2 = encryptedhalfs[16:] #2. Derive the decryption key using scrypt key = scrypt.hash(passphrase, salt, 16384, 8, 8) derivedhalf1 = key[0:32] derivedhalf2 = key[32:64] #3. Aes decrypt the encrypted halves Aes = aes.Aes(derivedhalf2) xorhalf1 = Aes.dec(encryptedhalf1) xorhalf2 = Aes.dec(encryptedhalf2) #4 . xor them with the two halves of derivedhalf1 to get the original values half1 = enc.sxor(xorhalf1[:halflength], derivedhalf1[:16]) half2 = enc.sxor(xorhalf2[:(length - halflength)], derivedhalf1[16:32]) #5. build the address and check it against the check hash pub_address = half1 + half2 if salt != hashlib.sha256(hashlib.sha256(pub_address).digest()).digest()[:4]: return False, 'salt' #6. return the address as a single string return True, enc.b58encode(pub_address)
def intermediate2privK(intermediate_passphrase_string):
"""
Steps to create new encrypted private keys given intermediate_passphrase_string from owner
(so we have ownerentropy, and passpoint, but we do not have passfactor or the passphrase):
"""
#get ownerentropy and passpoint from the intermediate key
#check the checksum en route
decstring = enc.b58decode(intermediate_passphrase_string)
checksum = decstring[-4:]
if checksum != hashlib.sha256(hashlib.sha256(
decstring[:-4]).digest()).digest()[:4]:
return False, 'checksum'
decodedstring = decstring[:-4]
ownerentropy = decodedstring[8:16]
passpoint = decodedstring[-33:]
print(passpoint)
#1. Set flagbyte.
#Turn on bit 0x20 if the Bitcoin address will be formed by hashing the compressed public key (optional, saves space, but many Bitcoin implementations aren't compatible with it)
#Turn on bit 0x04 if ownerentropy contains a value for lotsequence.
#(While it has no effect on the keypair generation process, the decryption process needs this flag to know how to process ownerentropy)
flagbyte = chr(
0b00100000
) # 00 EC 1 compressed 00 future 0 has no lotsequence 00 future
#2. Generate 24 random bytes, call this seedb. Take SHA256(SHA256(seedb)) to yield 32 bytes, call this factorb.
seedb = os.urandom(24)
seedb = b'ABCDEFGHIJKLMNOPQRSTUVWX'
#seedb = bytearray(b'ABCDEFGHIJKLMNOPQRSTUVWX')
#for c in seedb: print(c)
factorb = hashlib.sha256(hashlib.sha256(seedb).digest()).digest()
#3. ECMultiply passpoint by factorb.
pub = elip.base10_multiply(enc.decode(passpoint, 256),
enc.decode(factorb, 256))
#4. Use the resulting EC point as a public key and hash it into a Bitcoin address using either compressed or uncompressed public key methodology
# (specify which methodology is used inside flagbyte).
# This is the generated Bitcoin address, call it generatedaddress.
publicKey = ('0' + str(2 + (pub[1] % 2)) + enc.encode(pub[0], 16, 64))
generatedaddress = address.publicKey2Address(
publicKey) ## TODO Remember to add in the currency details here
#5. Take the first four bytes of SHA256(SHA256(generatedaddress)) and call it addresshash.
addresshash = hashlib.sha256(
hashlib.sha256(generatedaddress).digest()).digest()[:4]
#6. Now we will encrypt seedb. Derive a second key from passpoint using scrypt
#Parameters: passphrase is passpoint provided from the first party (expressed in binary as 33 bytes).
# salt is addresshash + ownerentropy, n=1024, r=1, p=1, length=64. The "+" operator is concatenation.
encseedb = scrypt.hash(passpoint, addresshash + ownerentropy, 1024, 1, 1,
64)
#7. Split the result into two 32-byte halves and call them derivedhalf1 and derivedhalf2.
derivedhalf1 = encseedb[0:32]
derivedhalf2 = encseedb[32:64]
#8. Do AES256Encrypt(seedb[0...15] xor derivedhalf1[0...15], derivedhalf2), call the 16-byte result encryptedpart1
Aes = aes.Aes(derivedhalf2)
encryptedpart1 = Aes.enc(enc.sxor(seedb[:16], derivedhalf1[:16]))
#9. Do AES256Encrypt((encryptedpart1[8...15] + seedb[16...23]) xor derivedhalf1[16...31], derivedhalf2), call the 16-byte result encryptedpart2.
# The "+" operator is concatenation.
encryptedpart2 = Aes.enc(
enc.sxor(encryptedpart1[8:16] + seedb[16:24], derivedhalf1[16:32]))
#10. The encrypted private key is the Base58Check-encoded concatenation of the following, which totals 39 bytes without Base58 checksum:
#0x01 0x43 + flagbyte + addresshash + ownerentropy + encryptedpart1[0...7] + encryptedpart2
input = '\x01\x43' + flagbyte + addresshash + ownerentropy + encryptedpart1[
0:8] + encryptedpart2
checksum = hashlib.sha256(hashlib.sha256(input).digest()).digest()[:4]
BIPKey = enc.b58encode(input + checksum)
cnfrmcode = confirmationcode(flagbyte, addresshash, ownerentropy, factorb,
derivedhalf1, derivedhalf2)
return BIPKey, generatedaddress, cnfrmcode
