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Handle PKCS#5 padding in the gcrypt backend.

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This commit is contained in:
Guus Sliepen 2009-11-05 00:02:42 +01:00
parent d9b2ac6767
commit 08615e420b
2 changed files with 48 additions and 44 deletions
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91
src/gcrypt/cipher.c
View file

@ -107,11 +107,9 @@ static bool cipher_open(cipher_t *cipher, int algo, int mode) {
}
cipher->keylen = gcry_cipher_get_algo_keylen(algo);
if(mode == GCRY_CIPHER_MODE_ECB || mode == GCRY_CIPHER_MODE_CBC)
cipher->blklen = gcry_cipher_get_algo_blklen(algo);
else
cipher->blklen = 0;
cipher->blklen = gcry_cipher_get_algo_blklen(algo);
cipher->key = xmalloc(cipher->keylen + cipher->blklen);
cipher->padding = mode == GCRY_CIPHER_MODE_ECB || mode == GCRY_CIPHER_MODE_CBC;
return true;
}
@ -190,64 +188,69 @@ bool cipher_regenerate_key(cipher_t *cipher, bool encrypt) {
return true;
}
static bool cipher_add_padding(cipher_t *cipher, void *indata, size_t inlen, size_t *outlen) {
size_t reqlen;
if(cipher->blklen == 1) {
*outlen = inlen;
return true;
}
reqlen = ((inlen + 1) / cipher->blklen) * cipher->blklen;
if(reqlen > *outlen)
return false;
// add padding
*outlen = reqlen;
return true;
}
static bool cipher_remove_padding(cipher_t *cipher, void *indata, size_t inlen, size_t *outlen) {
size_t origlen;
if(cipher->blklen == 1) {
*outlen = inlen;
return true;
}
if(inlen % cipher->blklen)
return false;
// check and remove padding
*outlen = origlen;
return true;
}
bool cipher_encrypt(cipher_t *cipher, const void *indata, size_t inlen, void *outdata, size_t *outlen, bool oneshot) {
gcry_error_t err;
uint8_t pad[cipher->blklen];
// To be fixed
if(cipher->padding) {
if(!oneshot)
return false;
if((err = gcry_cipher_encrypt(cipher->handle, outdata, inlen, indata, inlen))) {
size_t reqlen = ((inlen + 1) / cipher->blklen) * cipher->blklen;
uint8_t padbyte = reqlen - inlen;
inlen = reqlen - cipher->blklen;
for(int i = 0; i < cipher->blklen; i++)
if(i < cipher->blklen - padbyte)
pad[i] = ((uint8_t *)indata)[inlen + i];
else
pad[i] = padbyte;
}
if((err = gcry_cipher_encrypt(cipher->handle, outdata, *outlen, indata, inlen))) {
logger(LOG_ERR, "Error while encrypting: %s", gcry_strerror(err));
return false;
}
if(cipher->padding) {
if((err = gcry_cipher_encrypt(cipher->handle, outdata + inlen, cipher->blklen, pad, cipher->blklen))) {
logger(LOG_ERR, "Error while encrypting: %s", gcry_strerror(err));
return false;
}
inlen += cipher->blklen;
}
*outlen = inlen;
return true;
}
bool cipher_decrypt(cipher_t *cipher, const void *indata, size_t inlen, void *outdata, size_t *outlen, bool oneshot) {
gcry_error_t err;
// To be fixed
if((err = gcry_cipher_decrypt(cipher->handle, outdata, inlen, indata, inlen))) {
if((err = gcry_cipher_decrypt(cipher->handle, outdata, *outlen, indata, inlen))) {
logger(LOG_ERR, "Error while decrypting: %s", gcry_strerror(err));
return false;
}
if(cipher->padding) {
if(!oneshot)
return false;
uint8_t padbyte = ((uint8_t *)outdata)[inlen - 1];
if(padbyte == 0 || padbyte > cipher->blklen || padbyte > inlen)
return false;
size_t origlen = inlen - padbyte;
for(int i = inlen - 1; i >= origlen; i--)
if(((uint8_t *)indata)[i] != padbyte)
return false;
*outlen = origlen;
}
return true;
}

1
src/gcrypt/cipher.h
View file

@ -32,6 +32,7 @@ typedef struct cipher {
int nid;
uint16_t keylen;
uint16_t blklen;
bool padding;
} cipher_t;
extern bool cipher_open_by_name(struct cipher *, const char *);