def unpackage(src_uid, dst_uid, package_b64):
# b64 decode the package for decryption.
package = base64.b64decode(package_b64)
if not csc.yn_prompt("Are you sure you want\nto decrypt a message?"):
return {
"success": False,
"error": "User rejected pad read request.",
}
try:
pre = crypto.pre_unpackage(package, verbose=True)
except crypto.CryptoError:
traceback.print_exc()
return {
"success" : False,
"error": "Decryption failed.",
}
message_length = pre["message_length"]
p_text_index = pre["p_text_index"]
try:
skip_detected = read.decrypt_index_skipped(src_uid, dst_uid, p_text_index)
reuse_detected = read.decrypt_index_used(src_uid, dst_uid, p_text_index)
start_index = next_index = p_text_index
(p_text, next_index) = read.read_decrypt_pad(src_uid, dst_uid,
next_index, message_length)
(p_body, next_index) = read.read_decrypt_pad(src_uid, dst_uid,
next_index, message_length + crypto.TAG_LENGTH)
(p_tag_key, _) = read.read_decrypt_pad(src_uid, dst_uid,
next_index, crypto.TAG_KEY_LENGTH)
except metadata.NoMetadataException:
return {
"success": False,
"error": "Shared pad not found.",
}
try:
message = crypto.unpackage(package, p_text, p_body, p_tag_key, verbose=True)
return {
"success": True,
"message": message,
"skip_detected": skip_detected,
"reuse_detected": reuse_detected,
}
except crypto.IntegrityError:
traceback.print_exc()
logging.error("Integrity error in message from {} to {} with index {}".format(
src_uid, dst_uid, start_index))
return {
"success": False,
"error":"Decryption failed.", # Don't tell client specifics.
}
except crypto.CryptoError:
traceback.print_exc()
return {
"success": False,
"error":"Decryption failed.",
}
def test_package_reflexive(self):
message = "Test that packaged and unpackaging returns the same message"
index = 0
p_text = "otuhixnuheotuheouaoecgudoaeuteoahduao',.peaecd'983d uaoeuhu" #pseudo random typing
p_body = ",'cd.ucr,'.gud.,9'ud249 l3uf19842gfpd4gdu r9'7i3pkur84gciudr.g,fi r138uf927 i'e7pduxanw;jk8"
p_tag_key = "N\xbb\xcf\xb0jT\x81\x12X2.\xe5zMi\xee"
self.assertEquals(len(p_body), len(p_text)+crypto.TAG_LENGTH)
package = crypto.package(index, message, p_text, p_body, p_tag_key)
unpackage = crypto.unpackage(package, p_text, p_body, p_tag_key)
self.assertEquals(unpackage, message)
