/* Copyright 2014, Kenneth MacKay. Licensed under the BSD 2-clause license. */ | |

#ifndef _UECC_H_ | |

#define _UECC_H_ | |

#include <stdint.h> | |

/* Platform selection options. | |

If uECC_PLATFORM is not defined, the code will try to guess it based on compiler macros. | |

Possible values for uECC_PLATFORM are defined below: */ | |

#define uECC_arch_other 0 | |

#define uECC_x86 1 | |

#define uECC_x86_64 2 | |

#define uECC_arm 3 | |

#define uECC_arm_thumb 4 | |

#define uECC_arm_thumb2 5 | |

#define uECC_arm64 6 | |

#define uECC_avr 7 | |

/* If desired, you can define uECC_WORD_SIZE as appropriate for your platform (1, 4, or 8 bytes). | |

If uECC_WORD_SIZE is not explicitly defined then it will be automatically set based on your | |

platform. */ | |

/* Optimization level; trade speed for code size. | |

Larger values produce code that is faster but larger. | |

Currently supported values are 0 - 4; 0 is unusably slow for most applications. | |

Optimization level 4 currently only has an effect ARM platforms where more than one | |

curve is enabled. */ | |

#ifndef uECC_OPTIMIZATION_LEVEL | |

#define uECC_OPTIMIZATION_LEVEL 2 | |

#endif | |

/* uECC_SQUARE_FUNC - If enabled (defined as nonzero), this will cause a specific function to be | |

used for (scalar) squaring instead of the generic multiplication function. This can make things | |

faster somewhat faster, but increases the code size. */ | |

#ifndef uECC_SQUARE_FUNC | |

#define uECC_SQUARE_FUNC 0 | |

#endif | |

/* uECC_VLI_NATIVE_LITTLE_ENDIAN - If enabled (defined as nonzero), this will switch to native | |

little-endian format for *all* arrays passed in and out of the public API. This includes public | |

and private keys, shared secrets, signatures and message hashes. | |

Using this switch reduces the amount of call stack memory used by uECC, since less intermediate | |

translations are required. | |

Note that this will *only* work on native little-endian processors and it will treat the uint8_t | |

arrays passed into the public API as word arrays, therefore requiring the provided byte arrays | |

to be word aligned on architectures that do not support unaligned accesses. | |

IMPORTANT: Keys and signatures generated with uECC_VLI_NATIVE_LITTLE_ENDIAN=1 are incompatible | |

with keys and signatures generated with uECC_VLI_NATIVE_LITTLE_ENDIAN=0; all parties must use | |

the same endianness. */ | |

#ifndef uECC_VLI_NATIVE_LITTLE_ENDIAN | |

#define uECC_VLI_NATIVE_LITTLE_ENDIAN 0 | |

#endif | |

/* Curve support selection. Set to 0 to remove that curve. */ | |

#ifndef uECC_SUPPORTS_secp160r1 | |

#define uECC_SUPPORTS_secp160r1 1 | |

#endif | |

#ifndef uECC_SUPPORTS_secp192r1 | |

#define uECC_SUPPORTS_secp192r1 1 | |

#endif | |

#ifndef uECC_SUPPORTS_secp224r1 | |

#define uECC_SUPPORTS_secp224r1 1 | |

#endif | |

#ifndef uECC_SUPPORTS_secp256r1 | |

#define uECC_SUPPORTS_secp256r1 1 | |

#endif | |

#ifndef uECC_SUPPORTS_secp256k1 | |

#define uECC_SUPPORTS_secp256k1 1 | |

#endif | |

/* Specifies whether compressed point format is supported. | |

Set to 0 to disable point compression/decompression functions. */ | |

#ifndef uECC_SUPPORT_COMPRESSED_POINT | |

#define uECC_SUPPORT_COMPRESSED_POINT 1 | |

#endif | |

struct uECC_Curve_t; | |

typedef const struct uECC_Curve_t * uECC_Curve; | |

#ifdef __cplusplus | |

extern "C" | |

{ | |

#endif | |

#if uECC_SUPPORTS_secp160r1 | |

uECC_Curve uECC_secp160r1(void); | |

#endif | |

#if uECC_SUPPORTS_secp192r1 | |

uECC_Curve uECC_secp192r1(void); | |

#endif | |

#if uECC_SUPPORTS_secp224r1 | |

uECC_Curve uECC_secp224r1(void); | |

#endif | |

#if uECC_SUPPORTS_secp256r1 | |

uECC_Curve uECC_secp256r1(void); | |

#endif | |

#if uECC_SUPPORTS_secp256k1 | |

uECC_Curve uECC_secp256k1(void); | |

#endif | |

/* uECC_RNG_Function type | |

The RNG function should fill 'size' random bytes into 'dest'. It should return 1 if | |

'dest' was filled with random data, or 0 if the random data could not be generated. | |

The filled-in values should be either truly random, or from a cryptographically-secure PRNG. | |

A correctly functioning RNG function must be set (using uECC_set_rng()) before calling | |

uECC_make_key() or uECC_sign(). | |

Setting a correctly functioning RNG function improves the resistance to side-channel attacks | |

for uECC_shared_secret() and uECC_sign_deterministic(). | |

A correct RNG function is set by default when building for Windows, Linux, or OS X. | |

If you are building on another POSIX-compliant system that supports /dev/random or /dev/urandom, | |

you can define uECC_POSIX to use the predefined RNG. For embedded platforms there is no predefined | |

RNG function; you must provide your own. | |

*/ | |

typedef int (*uECC_RNG_Function)(uint8_t *dest, unsigned size); | |

/* uECC_set_rng() function. | |

Set the function that will be used to generate random bytes. The RNG function should | |

return 1 if the random data was generated, or 0 if the random data could not be generated. | |

On platforms where there is no predefined RNG function (eg embedded platforms), this must | |

be called before uECC_make_key() or uECC_sign() are used. | |

Inputs: | |

rng_function - The function that will be used to generate random bytes. | |

*/ | |

void uECC_set_rng(uECC_RNG_Function rng_function); | |

/* uECC_get_rng() function. | |

Returns the function that will be used to generate random bytes. | |

*/ | |

uECC_RNG_Function uECC_get_rng(void); | |

/* uECC_curve_private_key_size() function. | |

Returns the size of a private key for the curve in bytes. | |

*/ | |

int uECC_curve_private_key_size(uECC_Curve curve); | |

/* uECC_curve_public_key_size() function. | |

Returns the size of a public key for the curve in bytes. | |

*/ | |

int uECC_curve_public_key_size(uECC_Curve curve); | |

/* uECC_make_key() function. | |

Create a public/private key pair. | |

Outputs: | |

public_key - Will be filled in with the public key. Must be at least 2 * the curve size | |

(in bytes) long. For example, if the curve is secp256r1, public_key must be 64 | |

bytes long. | |

private_key - Will be filled in with the private key. Must be as long as the curve order; this | |

is typically the same as the curve size, except for secp160r1. For example, if the | |

curve is secp256r1, private_key must be 32 bytes long. | |

For secp160r1, private_key must be 21 bytes long! Note that the first byte will | |

almost always be 0 (there is about a 1 in 2^80 chance of it being non-zero). | |

Returns 1 if the key pair was generated successfully, 0 if an error occurred. | |

*/ | |

int uECC_make_key(uint8_t *public_key, uint8_t *private_key, uECC_Curve curve); | |

/* uECC_shared_secret() function. | |

Compute a shared secret given your secret key and someone else's public key. If the public key | |

is not from a trusted source and has not been previously verified, you should verify it first | |

using uECC_valid_public_key(). | |

Note: It is recommended that you hash the result of uECC_shared_secret() before using it for | |

symmetric encryption or HMAC. | |

Inputs: | |

public_key - The public key of the remote party. | |

private_key - Your private key. | |

Outputs: | |

secret - Will be filled in with the shared secret value. Must be the same size as the | |

curve size; for example, if the curve is secp256r1, secret must be 32 bytes long. | |

Returns 1 if the shared secret was generated successfully, 0 if an error occurred. | |

*/ | |

int uECC_shared_secret(const uint8_t *public_key, | |

const uint8_t *private_key, | |

uint8_t *secret, | |

uECC_Curve curve); | |

#if uECC_SUPPORT_COMPRESSED_POINT | |

/* uECC_compress() function. | |

Compress a public key. | |

Inputs: | |

public_key - The public key to compress. | |

Outputs: | |

compressed - Will be filled in with the compressed public key. Must be at least | |

(curve size + 1) bytes long; for example, if the curve is secp256r1, | |

compressed must be 33 bytes long. | |

*/ | |

void uECC_compress(const uint8_t *public_key, uint8_t *compressed, uECC_Curve curve); | |

/* uECC_decompress() function. | |

Decompress a compressed public key. | |

Inputs: | |

compressed - The compressed public key. | |

Outputs: | |

public_key - Will be filled in with the decompressed public key. | |

*/ | |

void uECC_decompress(const uint8_t *compressed, uint8_t *public_key, uECC_Curve curve); | |

#endif /* uECC_SUPPORT_COMPRESSED_POINT */ | |

/* uECC_valid_public_key() function. | |

Check to see if a public key is valid. | |

Note that you are not required to check for a valid public key before using any other uECC | |

functions. However, you may wish to avoid spending CPU time computing a shared secret or | |

verifying a signature using an invalid public key. | |

Inputs: | |

public_key - The public key to check. | |

Returns 1 if the public key is valid, 0 if it is invalid. | |

*/ | |

int uECC_valid_public_key(const uint8_t *public_key, uECC_Curve curve); | |

/* uECC_compute_public_key() function. | |

Compute the corresponding public key for a private key. | |

Inputs: | |

private_key - The private key to compute the public key for | |

Outputs: | |

public_key - Will be filled in with the corresponding public key | |

Returns 1 if the key was computed successfully, 0 if an error occurred. | |

*/ | |

int uECC_compute_public_key(const uint8_t *private_key, uint8_t *public_key, uECC_Curve curve); | |

/* uECC_sign() function. | |

Generate an ECDSA signature for a given hash value. | |

Usage: Compute a hash of the data you wish to sign (SHA-2 is recommended) and pass it in to | |

this function along with your private key. | |

Inputs: | |

private_key - Your private key. | |

message_hash - The hash of the message to sign. | |

hash_size - The size of message_hash in bytes. | |

Outputs: | |

signature - Will be filled in with the signature value. Must be at least 2 * curve size long. | |

For example, if the curve is secp256r1, signature must be 64 bytes long. | |

Returns 1 if the signature generated successfully, 0 if an error occurred. | |

*/ | |

int uECC_sign(const uint8_t *private_key, | |

const uint8_t *message_hash, | |

unsigned hash_size, | |

uint8_t *signature, | |

uECC_Curve curve); | |

/* uECC_HashContext structure. | |

This is used to pass in an arbitrary hash function to uECC_sign_deterministic(). | |

The structure will be used for multiple hash computations; each time a new hash | |

is computed, init_hash() will be called, followed by one or more calls to | |

update_hash(), and finally a call to finish_hash() to produce the resulting hash. | |

The intention is that you will create a structure that includes uECC_HashContext | |

followed by any hash-specific data. For example: | |

typedef struct SHA256_HashContext { | |

uECC_HashContext uECC; | |

SHA256_CTX ctx; | |

} SHA256_HashContext; | |

void init_SHA256(uECC_HashContext *base) { | |

SHA256_HashContext *context = (SHA256_HashContext *)base; | |

SHA256_Init(&context->ctx); | |

} | |

void update_SHA256(uECC_HashContext *base, | |

const uint8_t *message, | |

unsigned message_size) { | |

SHA256_HashContext *context = (SHA256_HashContext *)base; | |

SHA256_Update(&context->ctx, message, message_size); | |

} | |

void finish_SHA256(uECC_HashContext *base, uint8_t *hash_result) { | |

SHA256_HashContext *context = (SHA256_HashContext *)base; | |

SHA256_Final(hash_result, &context->ctx); | |

} | |

... when signing ... | |

{ | |

uint8_t tmp[32 + 32 + 64]; | |

SHA256_HashContext ctx = {{&init_SHA256, &update_SHA256, &finish_SHA256, 64, 32, tmp}}; | |

uECC_sign_deterministic(key, message_hash, &ctx.uECC, signature); | |

} | |

*/ | |

typedef struct uECC_HashContext { | |

void (*init_hash)(const struct uECC_HashContext *context); | |

void (*update_hash)(const struct uECC_HashContext *context, | |

const uint8_t *message, | |

unsigned message_size); | |

void (*finish_hash)(const struct uECC_HashContext *context, uint8_t *hash_result); | |

unsigned block_size; /* Hash function block size in bytes, eg 64 for SHA-256. */ | |

unsigned result_size; /* Hash function result size in bytes, eg 32 for SHA-256. */ | |

uint8_t *tmp; /* Must point to a buffer of at least (2 * result_size + block_size) bytes. */ | |

} uECC_HashContext; | |

/* uECC_sign_deterministic() function. | |

Generate an ECDSA signature for a given hash value, using a deterministic algorithm | |

(see RFC 6979). You do not need to set the RNG using uECC_set_rng() before calling | |

this function; however, if the RNG is defined it will improve resistance to side-channel | |

attacks. | |

Usage: Compute a hash of the data you wish to sign (SHA-2 is recommended) and pass it to | |

this function along with your private key and a hash context. Note that the message_hash | |

does not need to be computed with the same hash function used by hash_context. | |

Inputs: | |

private_key - Your private key. | |

message_hash - The hash of the message to sign. | |

hash_size - The size of message_hash in bytes. | |

hash_context - A hash context to use. | |

Outputs: | |

signature - Will be filled in with the signature value. | |

Returns 1 if the signature generated successfully, 0 if an error occurred. | |

*/ | |

int uECC_sign_deterministic(const uint8_t *private_key, | |

const uint8_t *message_hash, | |

unsigned hash_size, | |

const uECC_HashContext *hash_context, | |

uint8_t *signature, | |

uECC_Curve curve); | |

/* uECC_verify() function. | |

Verify an ECDSA signature. | |

Usage: Compute the hash of the signed data using the same hash as the signer and | |

pass it to this function along with the signer's public key and the signature values (r and s). | |

Inputs: | |

public_key - The signer's public key. | |

message_hash - The hash of the signed data. | |

hash_size - The size of message_hash in bytes. | |

signature - The signature value. | |

Returns 1 if the signature is valid, 0 if it is invalid. | |

*/ | |

int uECC_verify(const uint8_t *public_key, | |

const uint8_t *message_hash, | |

unsigned hash_size, | |

const uint8_t *signature, | |

uECC_Curve curve); | |

#ifdef __cplusplus | |

} /* end of extern "C" */ | |

#endif | |

#endif /* _UECC_H_ */ |