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125 lines
3.7 KiB
Cython
125 lines
3.7 KiB
Cython
"""A thin OpenSSL wrapper
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This could be replaced by PyCrypto or something similar when the performance
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of their PBKDF2 implementation is comparable to the OpenSSL version.
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"""
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from libc.stdlib cimport malloc, free
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API_VERSION = 2
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cdef extern from "openssl/rand.h":
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int RAND_bytes(unsigned char *buf,int num)
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cdef extern from "openssl/evp.h":
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ctypedef struct EVP_MD:
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pass
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ctypedef struct EVP_CIPHER:
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pass
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ctypedef struct EVP_CIPHER_CTX:
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unsigned char *iv
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pass
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ctypedef struct ENGINE:
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pass
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const EVP_MD *EVP_sha256()
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const EVP_CIPHER *EVP_aes_256_ctr()
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void EVP_CIPHER_CTX_init(EVP_CIPHER_CTX *a)
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void EVP_CIPHER_CTX_cleanup(EVP_CIPHER_CTX *a)
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int EVP_EncryptInit_ex(EVP_CIPHER_CTX *ctx,const EVP_CIPHER *cipher, ENGINE *impl,
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const unsigned char *key, const unsigned char *iv)
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int EVP_EncryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
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int *outl, const unsigned char *in_, int inl)
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int PKCS5_PBKDF2_HMAC(const char *password, int passwordlen,
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const unsigned char *salt, int saltlen, int iter,
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const EVP_MD *digest,
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int keylen, unsigned char *out)
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import struct
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_int = struct.Struct('>I')
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_long = struct.Struct('>Q')
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bytes_to_int = lambda x, offset=0: _int.unpack_from(x, offset)[0]
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bytes_to_long = lambda x, offset=0: _long.unpack_from(x, offset)[0]
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long_to_bytes = lambda x: _long.pack(x)
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def num_aes_blocks(length):
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"""Return the number of AES blocks required to encrypt/decrypt *length* bytes of data
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"""
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return (length + 15) // 16
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def pbkdf2_sha256(password, salt, iterations, size):
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"""Password based key derivation function 2 (RFC2898)
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"""
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cdef unsigned char *key = <unsigned char *>malloc(size)
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if not key:
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raise MemoryError
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try:
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rv = PKCS5_PBKDF2_HMAC(password, len(password), salt, len(salt), iterations, EVP_sha256(), size, key)
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if not rv:
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raise Exception('PKCS5_PBKDF2_HMAC failed')
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return key[:size]
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finally:
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free(key)
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def get_random_bytes(n):
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"""Return n cryptographically strong pseudo-random bytes
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"""
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cdef unsigned char *buf = <unsigned char *>malloc(n)
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if not buf:
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raise MemoryError
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try:
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if RAND_bytes(buf, n) < 1:
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raise Exception('RAND_bytes failed')
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return buf[:n]
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finally:
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free(buf)
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cdef class AES:
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"""A thin wrapper around the OpenSSL EVP cipher API
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"""
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cdef EVP_CIPHER_CTX ctx
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def __cinit__(self, key, iv=None):
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EVP_CIPHER_CTX_init(&self.ctx)
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if not EVP_EncryptInit_ex(&self.ctx, EVP_aes_256_ctr(), NULL, NULL, NULL):
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raise Exception('EVP_EncryptInit_ex failed')
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self.reset(key, iv)
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def __dealloc__(self):
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EVP_CIPHER_CTX_cleanup(&self.ctx)
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def reset(self, key=None, iv=None):
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cdef const unsigned char *key2 = NULL
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cdef const unsigned char *iv2 = NULL
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if key:
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key2 = key
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if iv:
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iv2 = iv
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if not EVP_EncryptInit_ex(&self.ctx, NULL, NULL, key2, iv2):
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raise Exception('EVP_EncryptInit_ex failed')
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@property
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def iv(self):
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return self.ctx.iv[:16]
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def encrypt(self, data):
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cdef int inl = len(data)
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cdef int outl
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cdef unsigned char *out = <unsigned char *>malloc(inl)
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if not out:
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raise MemoryError
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try:
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if not EVP_EncryptUpdate(&self.ctx, out, &outl, data, inl):
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raise Exception('EVP_EncryptUpdate failed')
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return out[:inl]
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finally:
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free(out)
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decrypt = encrypt
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