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vfdecrypt: OpenSSL 1.1 compatibility
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Allocate contexts from the heap on all OpenSSL versions, this is needed
since OpenSSL 1.1.0. No attempt is done at addressing issues like global
variables and fixing potential memleaks on error paths.

Compile-tested only with OpenSSL 1.1.0e (Arch Linux) and OpenSSL 1.0.2g
(Ubuntu 16.04), I have no test file.

Fixes #4
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@Lekensteyn
Lekensteyn committed May 2, 2017
1 parent fc9b304 commit f16f247
Showing 1 changed file with 80 additions and 23 deletions.
103 changes: 80 additions & 23 deletions vfdecrypt.c
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Original file line number Diff line number Diff line change
Expand Up @@ -183,7 +183,7 @@ void adjust_v2_header_byteorder(cencrypted_v2_pwheader *pwhdr) {
pwhdr->encrypted_keyblob_size = htonl(pwhdr->encrypted_keyblob_size);
}

HMAC_CTX hmacsha1_ctx;
HMAC_CTX *hmacsha1_ctx;
AES_KEY aes_decrypt_key;
int CHUNK_SIZE=4096; // default

Expand All @@ -196,9 +196,9 @@ void compute_iv(uint32_t chunk_no, uint8_t *iv) {
unsigned int mdLen;

chunk_no = OSSwapHostToBigInt32(chunk_no);
HMAC_Init_ex(&hmacsha1_ctx, NULL, 0, NULL, NULL);
HMAC_Update(&hmacsha1_ctx, (void *) &chunk_no, sizeof(uint32_t));
HMAC_Final(&hmacsha1_ctx, mdResult, &mdLen);
HMAC_Init_ex(hmacsha1_ctx, NULL, 0, NULL, NULL);
HMAC_Update(hmacsha1_ctx, (void *) &chunk_no, sizeof(uint32_t));
HMAC_Final(hmacsha1_ctx, mdResult, &mdLen);
memcpy(iv, mdResult, CIPHER_BLOCKSIZE);
}

Expand All @@ -212,52 +212,75 @@ void decrypt_chunk(uint8_t *ctext, uint8_t *ptext, uint32_t chunk_no) {
/* DES3-EDE unwrap operation loosely based on to RFC 2630, section 12.6
* wrapped_key has to be 40 bytes in length. */
int apple_des3_ede_unwrap_key(uint8_t *wrapped_key, int wrapped_key_len, uint8_t *decryptKey, uint8_t *unwrapped_key) {
EVP_CIPHER_CTX ctx;
EVP_CIPHER_CTX *ctx;
uint8_t *TEMP1, *TEMP2, *CEKICV;
uint8_t IV[8] = { 0x4a, 0xdd, 0xa2, 0x2c, 0x79, 0xe8, 0x21, 0x05 };
int outlen, tmplen, i;

EVP_CIPHER_CTX_init(&ctx);
#if OPENSSL_VERSION_NUMBER >= 0x10100000L
ctx = EVP_CIPHER_CTX_new();
#else
ctx = malloc(sizeof(*ctx));
#endif
if (!ctx) {
fprintf(stderr, "Out of memory: EVP_CIPHER_CTX!\n");
return(-1);
}

EVP_CIPHER_CTX_init(ctx);
/* result of the decryption operation shouldn't be bigger than ciphertext */
TEMP1 = malloc(wrapped_key_len);
TEMP2 = malloc(wrapped_key_len);
CEKICV = malloc(wrapped_key_len);
/* uses PKCS#7 padding for symmetric key operations by default */
EVP_DecryptInit_ex(&ctx, EVP_des_ede3_cbc(), NULL, decryptKey, IV);
EVP_DecryptInit_ex(ctx, EVP_des_ede3_cbc(), NULL, decryptKey, IV);

if(!EVP_DecryptUpdate(&ctx, TEMP1, &outlen, wrapped_key, wrapped_key_len)) {
if(!EVP_DecryptUpdate(ctx, TEMP1, &outlen, wrapped_key, wrapped_key_len)) {
fprintf(stderr, "internal error (1) during key unwrap operation!\n");
return(-1);
}
if(!EVP_DecryptFinal_ex(&ctx, TEMP1 + outlen, &tmplen)) {
if(!EVP_DecryptFinal_ex(ctx, TEMP1 + outlen, &tmplen)) {
fprintf(stderr, "internal error (2) during key unwrap operation!\n");
return(-1);
}
outlen += tmplen;
EVP_CIPHER_CTX_cleanup(&ctx);
#if OPENSSL_VERSION_NUMBER >= 0x10100000L
EVP_CIPHER_CTX_reset(ctx);
#else
EVP_CIPHER_CTX_cleanup(ctx);
#endif

/* reverse order of TEMP3 */
for(i = 0; i < outlen; i++) TEMP2[i] = TEMP1[outlen - i - 1];

EVP_CIPHER_CTX_init(&ctx);
EVP_CIPHER_CTX_init(ctx);
/* uses PKCS#7 padding for symmetric key operations by default */
EVP_DecryptInit_ex(&ctx, EVP_des_ede3_cbc(), NULL, decryptKey, TEMP2);
if(!EVP_DecryptUpdate(&ctx, CEKICV, &outlen, TEMP2+8, outlen-8)) {
EVP_DecryptInit_ex(ctx, EVP_des_ede3_cbc(), NULL, decryptKey, TEMP2);
if(!EVP_DecryptUpdate(ctx, CEKICV, &outlen, TEMP2+8, outlen-8)) {
fprintf(stderr, "internal error (3) during key unwrap operation!\n");
return(-1);
}
if(!EVP_DecryptFinal_ex(&ctx, CEKICV + outlen, &tmplen)) {
if(!EVP_DecryptFinal_ex(ctx, CEKICV + outlen, &tmplen)) {
fprintf(stderr, "internal error (4) during key unwrap operation!\n");
return(-1);
}

outlen += tmplen;
EVP_CIPHER_CTX_cleanup(&ctx);
#if OPENSSL_VERSION_NUMBER >= 0x10100000L
EVP_CIPHER_CTX_reset(ctx);
#else
EVP_CIPHER_CTX_cleanup(ctx);
#endif

memcpy(unwrapped_key, CEKICV+4, outlen-4);
free(TEMP1);
free(TEMP2);
free(CEKICV);
#if OPENSSL_VERSION_NUMBER >= 0x10100000L
EVP_CIPHER_CTX_free(ctx);
#else
free(ctx);
#endif
return(0);
}

Expand All @@ -279,31 +302,46 @@ int unwrap_v1_header(char *passphrase, cencrypted_v1_header *header, uint8_t *ae
int unwrap_v2_header(char *passphrase, cencrypted_v2_pwheader *header, uint8_t *aes_key, uint8_t *hmacsha1_key) {
/* derived key is a 3DES-EDE key */
uint8_t derived_key[192/8];
EVP_CIPHER_CTX ctx;
EVP_CIPHER_CTX *ctx;
uint8_t *TEMP1;
int outlen, tmplen;

#if OPENSSL_VERSION_NUMBER >= 0x10100000L
ctx = EVP_CIPHER_CTX_new();
#else
ctx = malloc(sizeof(*ctx));
#endif
if (!ctx) {
fprintf(stderr, "Out of memory: EVP_CIPHER_CTX!\n");
return(-1);
}

PKCS5_PBKDF2_HMAC_SHA1(passphrase, strlen(passphrase), (unsigned char*)header->kdf_salt, 20,
PBKDF2_ITERATION_COUNT, sizeof(derived_key), derived_key);

print_hex(derived_key, 192/8);

EVP_CIPHER_CTX_init(&ctx);
EVP_CIPHER_CTX_init(ctx);
/* result of the decryption operation shouldn't be bigger than ciphertext */
TEMP1 = malloc(header->encrypted_keyblob_size);
/* uses PKCS#7 padding for symmetric key operations by default */
EVP_DecryptInit_ex(&ctx, EVP_des_ede3_cbc(), NULL, derived_key, header->blob_enc_iv);
EVP_DecryptInit_ex(ctx, EVP_des_ede3_cbc(), NULL, derived_key, header->blob_enc_iv);

if(!EVP_DecryptUpdate(&ctx, TEMP1, &outlen, header->encrypted_keyblob, header->encrypted_keyblob_size)) {
if(!EVP_DecryptUpdate(ctx, TEMP1, &outlen, header->encrypted_keyblob, header->encrypted_keyblob_size)) {
fprintf(stderr, "internal error (1) during key unwrap operation!\n");
return(-1);
}
if(!EVP_DecryptFinal_ex(&ctx, TEMP1 + outlen, &tmplen)) {
if(!EVP_DecryptFinal_ex(ctx, TEMP1 + outlen, &tmplen)) {
fprintf(stderr, "internal error (2) during key unwrap operation!\n");
return(-1);
}
outlen += tmplen;
EVP_CIPHER_CTX_cleanup(&ctx);
#if OPENSSL_VERSION_NUMBER >= 0x10100000L
EVP_CIPHER_CTX_free(ctx);
#else
EVP_CIPHER_CTX_cleanup(ctx);
free(ctx);
#endif
memcpy(aes_key, TEMP1, 16);
memcpy(hmacsha1_key, TEMP1, 20);

Expand Down Expand Up @@ -446,8 +484,21 @@ int main(int argc, char *argv[]) {
CHUNK_SIZE = v2header.blocksize;
}

HMAC_CTX_init(&hmacsha1_ctx);
HMAC_Init_ex(&hmacsha1_ctx, hmacsha1_key, sizeof(hmacsha1_key), EVP_sha1(), NULL);
#if OPENSSL_VERSION_NUMBER >= 0x10100000L
hmacsha1_ctx = HMAC_CTX_new();
#else
hmacsha1_ctx = malloc(sizeof(*hmacsha1_ctx));
#endif
if (!hmacsha1_ctx) {
fprintf(stderr, "Out of memory: HMAC CTX!\n");
exit(1);
}
#if OPENSSL_VERSION_NUMBER >= 0x10100000L
HMAC_CTX_reset(hmacsha1_ctx);
#else
HMAC_CTX_init(hmacsha1_ctx);
#endif
HMAC_Init_ex(hmacsha1_ctx, hmacsha1_key, sizeof(hmacsha1_key), EVP_sha1(), NULL);
AES_set_decrypt_key(aes_key, CIPHER_KEY_LENGTH * 8, &aes_decrypt_key);

if (verbose >= 1) {
Expand All @@ -472,5 +523,11 @@ int main(int argc, char *argv[]) {
}

if (verbose) fprintf(stderr, "%"PRIX32" chunks written\n", chunk_no);
#if OPENSSL_VERSION_NUMBER >= 0x10100000L
HMAC_CTX_free(hmacsha1_ctx);
#else
HMAC_CTX_cleanup(hmacsha1_ctx);
free(hmacsha1_ctx);
#endif
return(0);
}

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