diff options
Diffstat (limited to 'keystore/blob.cpp')
| -rw-r--r-- | keystore/blob.cpp | 57 |
1 files changed, 39 insertions, 18 deletions
diff --git a/keystore/blob.cpp b/keystore/blob.cpp index 72f6493..0a72d5b 100644 --- a/keystore/blob.cpp +++ b/keystore/blob.cpp @@ -19,12 +19,12 @@ #include <arpa/inet.h> #include <errno.h> #include <fcntl.h> +#include <openssl/rand.h> #include <string.h> #include <cutils/log.h> #include "blob.h" -#include "entropy.h" #include "keystore_utils.h" @@ -60,16 +60,31 @@ class ArrayEraser { size_t mSize; }; +/** + * Returns a EVP_CIPHER appropriate for the given key, based on the key's size. + */ +const EVP_CIPHER* getAesCipherForKey(const std::vector<uint8_t>& key) { + const EVP_CIPHER* cipher = EVP_aes_256_gcm(); + if (key.size() == kAes128KeySizeBytes) { + cipher = EVP_aes_128_gcm(); + } + return cipher; +} + /* - * Encrypt 'len' data at 'in' with AES-GCM, using 128-bit key at 'key', 96-bit IV at 'iv' and write - * output to 'out' (which may be the same location as 'in') and 128-bit tag to 'tag'. + * Encrypt 'len' data at 'in' with AES-GCM, using 128-bit or 256-bit key at 'key', 96-bit IV at + * 'iv' and write output to 'out' (which may be the same location as 'in') and 128-bit tag to + * 'tag'. */ -ResponseCode AES_gcm_encrypt(const uint8_t* in, uint8_t* out, size_t len, const uint8_t* key, - const uint8_t* iv, uint8_t* tag) { - const EVP_CIPHER* cipher = EVP_aes_128_gcm(); +ResponseCode AES_gcm_encrypt(const uint8_t* in, uint8_t* out, size_t len, + const std::vector<uint8_t>& key, const uint8_t* iv, uint8_t* tag) { + + // There can be 128-bit and 256-bit keys + const EVP_CIPHER* cipher = getAesCipherForKey(key); + EVP_CIPHER_CTX_Ptr ctx(EVP_CIPHER_CTX_new()); - EVP_EncryptInit_ex(ctx.get(), cipher, nullptr /* engine */, key, iv); + EVP_EncryptInit_ex(ctx.get(), cipher, nullptr /* engine */, key.data(), iv); EVP_CIPHER_CTX_set_padding(ctx.get(), 0 /* no padding needed with GCM */); std::unique_ptr<uint8_t[]> out_tmp(new uint8_t[len]); @@ -93,15 +108,20 @@ ResponseCode AES_gcm_encrypt(const uint8_t* in, uint8_t* out, size_t len, const } /* - * Decrypt 'len' data at 'in' with AES-GCM, using 128-bit key at 'key', 96-bit IV at 'iv', checking - * 128-bit tag at 'tag' and writing plaintext to 'out' (which may be the same location as 'in'). + * Decrypt 'len' data at 'in' with AES-GCM, using 128-bit or 256-bit key at 'key', 96-bit IV at + * 'iv', checking 128-bit tag at 'tag' and writing plaintext to 'out'(which may be the same + * location as 'in'). */ -ResponseCode AES_gcm_decrypt(const uint8_t* in, uint8_t* out, size_t len, const uint8_t* key, - const uint8_t* iv, const uint8_t* tag) { - const EVP_CIPHER* cipher = EVP_aes_128_gcm(); +ResponseCode AES_gcm_decrypt(const uint8_t* in, uint8_t* out, size_t len, + const std::vector<uint8_t> key, const uint8_t* iv, + const uint8_t* tag) { + + // There can be 128-bit and 256-bit keys + const EVP_CIPHER* cipher = getAesCipherForKey(key); + EVP_CIPHER_CTX_Ptr ctx(EVP_CIPHER_CTX_new()); - EVP_DecryptInit_ex(ctx.get(), cipher, nullptr /* engine */, key, iv); + EVP_DecryptInit_ex(ctx.get(), cipher, nullptr /* engine */, key.data(), iv); EVP_CIPHER_CTX_set_padding(ctx.get(), 0 /* no padding needed with GCM */); EVP_CIPHER_CTX_ctrl(ctx.get(), EVP_CTRL_GCM_SET_TAG, kGcmTagLength, const_cast<uint8_t*>(tag)); @@ -205,8 +225,8 @@ void Blob::setFallback(bool fallback) { } } -ResponseCode Blob::writeBlob(const std::string& filename, const uint8_t* aes_key, State state, - Entropy* entropy) { +ResponseCode Blob::writeBlob(const std::string& filename, const std::vector<uint8_t>& aes_key, + State state) { ALOGV("writing blob %s", filename.c_str()); const size_t dataLength = mBlob.length; @@ -219,7 +239,7 @@ ResponseCode Blob::writeBlob(const std::string& filename, const uint8_t* aes_key } memset(mBlob.initialization_vector, 0, AES_BLOCK_SIZE); - if (!entropy->generate_random_data(mBlob.initialization_vector, kGcmIvSizeBytes)) { + if (!RAND_bytes(mBlob.initialization_vector, kGcmIvSizeBytes)) { ALOGW("Could not read random data for: %s", filename.c_str()); return ResponseCode::SYSTEM_ERROR; } @@ -255,7 +275,8 @@ ResponseCode Blob::writeBlob(const std::string& filename, const uint8_t* aes_key return ResponseCode::NO_ERROR; } -ResponseCode Blob::readBlob(const std::string& filename, const uint8_t* aes_key, State state) { +ResponseCode Blob::readBlob(const std::string& filename, const std::vector<uint8_t>& aes_key, + State state) { ALOGV("reading blob %s", filename.c_str()); const int in = TEMP_FAILURE_RETRY(open(filename.c_str(), O_RDONLY)); if (in < 0) { @@ -299,7 +320,7 @@ ResponseCode Blob::readBlob(const std::string& filename, const uint8_t* aes_key, } AES_KEY key; - AES_set_decrypt_key(aes_key, kAesKeySize * 8, &key); + AES_set_decrypt_key(aes_key.data(), kAesKeySize * 8, &key); AES_cbc_encrypt(blob.encrypted, blob.encrypted, encryptedLength, &key, blob.vector, AES_DECRYPT); key = {}; // clear key |