diff options
Diffstat (limited to 'youtube_dl/aes.py')
| -rw-r--r-- | youtube_dl/aes.py | 69 |
1 files changed, 66 insertions, 3 deletions
diff --git a/youtube_dl/aes.py b/youtube_dl/aes.py index a01c367de..a94a41079 100644 --- a/youtube_dl/aes.py +++ b/youtube_dl/aes.py @@ -1,13 +1,25 @@ from __future__ import unicode_literals -import base64 from math import ceil +from .compat import compat_b64decode from .utils import bytes_to_intlist, intlist_to_bytes BLOCK_SIZE_BYTES = 16 +def pkcs7_padding(data): + """ + PKCS#7 padding + + @param {int[]} data cleartext + @returns {int[]} padding data + """ + + remaining_length = BLOCK_SIZE_BYTES - len(data) % BLOCK_SIZE_BYTES + return data + [remaining_length] * remaining_length + + def aes_ctr_decrypt(data, key, counter): """ Decrypt with aes in counter mode @@ -60,6 +72,55 @@ def aes_cbc_decrypt(data, key, iv): return decrypted_data +def aes_cbc_encrypt(data, key, iv): + """ + Encrypt with aes in CBC mode. Using PKCS#7 padding + + @param {int[]} data cleartext + @param {int[]} key 16/24/32-Byte cipher key + @param {int[]} iv 16-Byte IV + @returns {int[]} encrypted data + """ + expanded_key = key_expansion(key) + block_count = int(ceil(float(len(data)) / BLOCK_SIZE_BYTES)) + + encrypted_data = [] + previous_cipher_block = iv + for i in range(block_count): + block = data[i * BLOCK_SIZE_BYTES: (i + 1) * BLOCK_SIZE_BYTES] + block = pkcs7_padding(block) + mixed_block = xor(block, previous_cipher_block) + + encrypted_block = aes_encrypt(mixed_block, expanded_key) + encrypted_data += encrypted_block + + previous_cipher_block = encrypted_block + + return encrypted_data + + +def aes_ecb_encrypt(data, key): + """ + Encrypt with aes in ECB mode. Using PKCS#7 padding + + @param {int[]} data cleartext + @param {int[]} key 16/24/32-Byte cipher key + @returns {int[]} encrypted data + """ + expanded_key = key_expansion(key) + block_count = int(ceil(float(len(data)) / BLOCK_SIZE_BYTES)) + + encrypted_data = [] + for i in range(block_count): + block = data[i * BLOCK_SIZE_BYTES: (i + 1) * BLOCK_SIZE_BYTES] + block = pkcs7_padding(block) + + encrypted_block = aes_encrypt(block, expanded_key) + encrypted_data += encrypted_block + + return encrypted_data + + def key_expansion(data): """ Generate key schedule @@ -152,7 +213,7 @@ def aes_decrypt_text(data, password, key_size_bytes): """ NONCE_LENGTH_BYTES = 8 - data = bytes_to_intlist(base64.b64decode(data.encode('utf-8'))) + data = bytes_to_intlist(compat_b64decode(data)) password = bytes_to_intlist(password.encode('utf-8')) key = password[:key_size_bytes] + [0] * (key_size_bytes - len(password)) @@ -174,6 +235,7 @@ def aes_decrypt_text(data, password, key_size_bytes): return plaintext + RCON = (0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36) SBOX = (0x63, 0x7C, 0x77, 0x7B, 0xF2, 0x6B, 0x6F, 0xC5, 0x30, 0x01, 0x67, 0x2B, 0xFE, 0xD7, 0xAB, 0x76, 0xCA, 0x82, 0xC9, 0x7D, 0xFA, 0x59, 0x47, 0xF0, 0xAD, 0xD4, 0xA2, 0xAF, 0x9C, 0xA4, 0x72, 0xC0, @@ -274,7 +336,7 @@ def xor(data1, data2): def rijndael_mul(a, b): - if(a == 0 or b == 0): + if (a == 0 or b == 0): return 0 return RIJNDAEL_EXP_TABLE[(RIJNDAEL_LOG_TABLE[a] + RIJNDAEL_LOG_TABLE[b]) % 0xFF] @@ -328,4 +390,5 @@ def inc(data): break return data + __all__ = ['aes_encrypt', 'key_expansion', 'aes_ctr_decrypt', 'aes_cbc_decrypt', 'aes_decrypt_text'] |
