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Diffstat (limited to 'lib/libavb/avb_crypto.h')
| -rw-r--r-- | lib/libavb/avb_crypto.h | 156 |
1 files changed, 156 insertions, 0 deletions
diff --git a/lib/libavb/avb_crypto.h b/lib/libavb/avb_crypto.h new file mode 100644 index 0000000000..cede08f1bc --- /dev/null +++ b/lib/libavb/avb_crypto.h @@ -0,0 +1,156 @@ +/* + * Copyright (C) 2016 The Android Open Source Project + * + * SPDX-License-Identifier: MIT + */ + +#if !defined(AVB_INSIDE_LIBAVB_H) && !defined(AVB_COMPILATION) +#error "Never include this file directly, include libavb.h instead." +#endif + +#ifndef AVB_CRYPTO_H_ +#define AVB_CRYPTO_H_ + +#include "avb_sysdeps.h" + +#ifdef __cplusplus +extern "C" { +#endif + +/* Size of a RSA-2048 signature. */ +#define AVB_RSA2048_NUM_BYTES 256 + +/* Size of a RSA-4096 signature. */ +#define AVB_RSA4096_NUM_BYTES 512 + +/* Size of a RSA-8192 signature. */ +#define AVB_RSA8192_NUM_BYTES 1024 + +/* Size in bytes of a SHA-1 digest. */ +#define AVB_SHA1_DIGEST_SIZE 20 + +/* Size in bytes of a SHA-256 digest. */ +#define AVB_SHA256_DIGEST_SIZE 32 + +/* Size in bytes of a SHA-512 digest. */ +#define AVB_SHA512_DIGEST_SIZE 64 + +/* Possible digest types supported by libavb routines. */ +typedef enum { + AVB_DIGEST_TYPE_SHA256, + AVB_DIGEST_TYPE_SHA512, +} AvbDigestType; + +/* Algorithms that can be used in the vbmeta image for + * verification. An algorithm consists of a hash type and a signature + * type. + * + * The data used to calculate the hash is the three blocks mentioned + * in the documentation for |AvbVBMetaImageHeader| except for the data + * in the "Authentication data" block. + * + * For signatures with RSA keys, PKCS v1.5 padding is used. The public + * key data is stored in the auxiliary data block, see + * |AvbRSAPublicKeyHeader| for the serialization format. + * + * Each algorithm type is described below: + * + * AVB_ALGORITHM_TYPE_NONE: There is no hash, no signature of the + * data, and no public key. The data cannot be verified. The fields + * |hash_size|, |signature_size|, and |public_key_size| must be zero. + * + * AVB_ALGORITHM_TYPE_SHA256_RSA2048: The hash function used is + * SHA-256, resulting in 32 bytes of hash digest data. This hash is + * signed with a 2048-bit RSA key. The field |hash_size| must be 32, + * |signature_size| must be 256, and the public key data must have + * |key_num_bits| set to 2048. + * + * AVB_ALGORITHM_TYPE_SHA256_RSA4096: Like above, but only with + * a 4096-bit RSA key and |signature_size| set to 512. + * + * AVB_ALGORITHM_TYPE_SHA256_RSA8192: Like above, but only with + * a 8192-bit RSA key and |signature_size| set to 1024. + * + * AVB_ALGORITHM_TYPE_SHA512_RSA2048: The hash function used is + * SHA-512, resulting in 64 bytes of hash digest data. This hash is + * signed with a 2048-bit RSA key. The field |hash_size| must be 64, + * |signature_size| must be 256, and the public key data must have + * |key_num_bits| set to 2048. + * + * AVB_ALGORITHM_TYPE_SHA512_RSA4096: Like above, but only with + * a 4096-bit RSA key and |signature_size| set to 512. + * + * AVB_ALGORITHM_TYPE_SHA512_RSA8192: Like above, but only with + * a 8192-bit RSA key and |signature_size| set to 1024. + */ +typedef enum { + AVB_ALGORITHM_TYPE_NONE, + AVB_ALGORITHM_TYPE_SHA256_RSA2048, + AVB_ALGORITHM_TYPE_SHA256_RSA4096, + AVB_ALGORITHM_TYPE_SHA256_RSA8192, + AVB_ALGORITHM_TYPE_SHA512_RSA2048, + AVB_ALGORITHM_TYPE_SHA512_RSA4096, + AVB_ALGORITHM_TYPE_SHA512_RSA8192, + _AVB_ALGORITHM_NUM_TYPES +} AvbAlgorithmType; + +/* Holds algorithm-specific data. The |padding| is needed by avb_rsa_verify. */ +typedef struct { + const uint8_t* padding; + size_t padding_len; + size_t hash_len; +} AvbAlgorithmData; + +/* Provides algorithm-specific data for a given |algorithm|. Returns NULL if + * |algorithm| is invalid. + */ +const AvbAlgorithmData* avb_get_algorithm_data(AvbAlgorithmType algorithm) + AVB_ATTR_WARN_UNUSED_RESULT; + +/* The header for a serialized RSA public key. + * + * The size of the key is given by |key_num_bits|, for example 2048 + * for a RSA-2048 key. By definition, a RSA public key is the pair (n, + * e) where |n| is the modulus (which can be represented in + * |key_num_bits| bits) and |e| is the public exponent. The exponent + * is not stored since it's assumed to always be 65537. + * + * To optimize verification, the key block includes two precomputed + * values, |n0inv| (fits in 32 bits) and |rr| and can always be + * represented in |key_num_bits|. + + * The value |n0inv| is the value -1/n[0] (mod 2^32). The value |rr| + * is (2^key_num_bits)^2 (mod n). + * + * Following this header is |key_num_bits| bits of |n|, then + * |key_num_bits| bits of |rr|. Both values are stored with most + * significant bit first. Each serialized number takes up + * |key_num_bits|/8 bytes. + * + * All fields in this struct are stored in network byte order when + * serialized. To generate a copy with fields swapped to native byte + * order, use the function avb_rsa_public_key_header_validate_and_byteswap(). + * + * The avb_rsa_verify() function expects a key in this serialized + * format. + * + * The 'avbtool extract_public_key' command can be used to generate a + * serialized RSA public key. + */ +typedef struct AvbRSAPublicKeyHeader { + uint32_t key_num_bits; + uint32_t n0inv; +} AVB_ATTR_PACKED AvbRSAPublicKeyHeader; + +/* Copies |src| to |dest| and validates, byte-swapping fields in the + * process if needed. Returns true if valid, false if invalid. + */ +bool avb_rsa_public_key_header_validate_and_byteswap( + const AvbRSAPublicKeyHeader* src, + AvbRSAPublicKeyHeader* dest) AVB_ATTR_WARN_UNUSED_RESULT; + +#ifdef __cplusplus +} +#endif + +#endif /* AVB_CRYPTO_H_ */ |