X-Git-Url: https://www.bearssl.org/gitweb//home/git/?p=BearSSL;a=blobdiff_plain;f=inc%2Fbearssl_ec.h;h=283be0f39af0aac2e69cc5aaf5547453e62ac0c9;hp=1ecb4cdcffe54b9347cc9f3454e0773c63e8c31e;hb=89ea3b1876d6a17a754c1f80c74f5076eccda866;hpb=693d2a0085f4c1d289cb6d79c02ddd23f18d9478
diff --git a/inc/bearssl_ec.h b/inc/bearssl_ec.h
index 1ecb4cd..283be0f 100644
--- a/inc/bearssl_ec.h
+++ b/inc/bearssl_ec.h
@@ -65,6 +65,11 @@
* Callback method that returns a pointer to the subgroup order for
* that curve. That value uses unsigned big-endian encoding.
*
+ * - `xoff()`
+ *
+ * Callback method that returns the offset and length of the X
+ * coordinate in an encoded point.
+ *
* - `mul()`
*
* Multiply a curve point with an integer.
@@ -294,6 +299,18 @@ typedef struct {
*/
const unsigned char *(*order)(int curve, size_t *len);
+ /**
+ * \brief Get the offset and length for the X coordinate.
+ *
+ * This function returns the offset and length (in bytes) of
+ * the X coordinate in an encoded non-zero point.
+ *
+ * \param curve curve identifier.
+ * \param len receiver for the X coordinate length (in bytes).
+ * \return the offset for the X coordinate (in bytes).
+ */
+ size_t (*xoff)(int curve, size_t *len);
+
/**
* \brief Multiply a curve point by an integer.
*
@@ -423,19 +440,69 @@ extern const br_ec_impl br_ec_p256_m15;
* \brief EC implementation "i15" (generic code) for Curve25519.
*
* This implementation uses the generic code for modular integers (with
- * 15-bit words) to support Curve25519. The `muladd()` method is not
- * implemented.
+ * 15-bit words) to support Curve25519. Due to the specificities of the
+ * curve definition, the following applies:
+ *
+ * - `muladd()` is not implemented (the function returns 0 systematically).
+ * - `order()` returns 2^255-1, since the point multiplication algorithm
+ * accepts any 32-bit integer as input (it clears the top bit and low
+ * three bits systematically).
*/
extern const br_ec_impl br_ec_c25519_i15;
+/**
+ * \brief EC implementation "i31" (generic code) for Curve25519.
+ *
+ * This implementation uses the generic code for modular integers (with
+ * 31-bit words) to support Curve25519. Due to the specificities of the
+ * curve definition, the following applies:
+ *
+ * - `muladd()` is not implemented (the function returns 0 systematically).
+ * - `order()` returns 2^255-1, since the point multiplication algorithm
+ * accepts any 32-bit integer as input (it clears the top bit and low
+ * three bits systematically).
+ */
+extern const br_ec_impl br_ec_c25519_i31;
+
/**
* \brief EC implementation "m15" (specialised code) for Curve25519.
*
* This implementation uses custom code relying on multiplication of
- * integers up to 15 bits. The `muladd()` method is not implemented.
+ * integers up to 15 bits. Due to the specificities of the curve
+ * definition, the following applies:
+ *
+ * - `muladd()` is not implemented (the function returns 0 systematically).
+ * - `order()` returns 2^255-1, since the point multiplication algorithm
+ * accepts any 32-bit integer as input (it clears the top bit and low
+ * three bits systematically).
*/
extern const br_ec_impl br_ec_c25519_m15;
+/**
+ * \brief EC implementation "m31" (specialised code) for Curve25519.
+ *
+ * This implementation uses custom code relying on multiplication of
+ * integers up to 31 bits. Due to the specificities of the curve
+ * definition, the following applies:
+ *
+ * - `muladd()` is not implemented (the function returns 0 systematically).
+ * - `order()` returns 2^255-1, since the point multiplication algorithm
+ * accepts any 32-bit integer as input (it clears the top bit and low
+ * three bits systematically).
+ */
+extern const br_ec_impl br_ec_c25519_m31;
+
+/**
+ * \brief Aggregate EC implementation "m15".
+ *
+ * This implementation is a wrapper for:
+ *
+ * - `br_ec_c25519_m15` for Curve25519
+ * - `br_ec_p256_m15` for NIST P-256
+ * - `br_ec_prime_i15` for other curves (NIST P-384 and NIST-P512)
+ */
+extern const br_ec_impl br_ec_all_m15;
+
/**
* \brief Convert a signature from "raw" to "asn1".
*