+ * RSA "i62" engine. Similar to i31, but internal multiplication use
+ * 64x64->128 multiplications. This is available only on architecture
+ * that offer such an opcode.
+ */
+
+/**
+ * \brief RSA public key engine "i62".
+ *
+ * This function is defined only on architecture that offer a 64x64->128
+ * opcode. Use `br_rsa_i62_public_get()` to dynamically obtain a pointer
+ * to that functiom.
+ *
+ * \see br_rsa_public
+ *
+ * \param x operand to exponentiate.
+ * \param xlen length of the operand (in bytes).
+ * \param pk RSA public key.
+ * \return 1 on success, 0 on error.
+ */
+uint32_t br_rsa_i62_public(unsigned char *x, size_t xlen,
+ const br_rsa_public_key *pk);
+
+/**
+ * \brief RSA signature verification engine "i62".
+ *
+ * This function is defined only on architecture that offer a 64x64->128
+ * opcode. Use `br_rsa_i62_pkcs1_vrfy_get()` to dynamically obtain a pointer
+ * to that functiom.
+ *
+ * \see br_rsa_pkcs1_vrfy
+ *
+ * \param x signature buffer.
+ * \param xlen signature length (in bytes).
+ * \param hash_oid encoded hash algorithm OID (or `NULL`).
+ * \param hash_len expected hash value length (in bytes).
+ * \param pk RSA public key.
+ * \param hash_out output buffer for the hash value.
+ * \return 1 on success, 0 on error.
+ */
+uint32_t br_rsa_i62_pkcs1_vrfy(const unsigned char *x, size_t xlen,
+ const unsigned char *hash_oid, size_t hash_len,
+ const br_rsa_public_key *pk, unsigned char *hash_out);
+
+/**
+ * \brief RSA private key engine "i62".
+ *
+ * This function is defined only on architecture that offer a 64x64->128
+ * opcode. Use `br_rsa_i62_private_get()` to dynamically obtain a pointer
+ * to that functiom.
+ *
+ * \see br_rsa_private
+ *
+ * \param x operand to exponentiate.
+ * \param sk RSA private key.
+ * \return 1 on success, 0 on error.
+ */
+uint32_t br_rsa_i62_private(unsigned char *x,
+ const br_rsa_private_key *sk);
+
+/**
+ * \brief RSA signature generation engine "i62".
+ *
+ * This function is defined only on architecture that offer a 64x64->128
+ * opcode. Use `br_rsa_i62_pkcs1_sign_get()` to dynamically obtain a pointer
+ * to that functiom.
+ *
+ * \see br_rsa_pkcs1_sign
+ *
+ * \param hash_oid encoded hash algorithm OID (or `NULL`).
+ * \param hash hash value.
+ * \param hash_len hash value length (in bytes).
+ * \param sk RSA private key.
+ * \param x output buffer for the hash value.
+ * \return 1 on success, 0 on error.
+ */
+uint32_t br_rsa_i62_pkcs1_sign(const unsigned char *hash_oid,
+ const unsigned char *hash, size_t hash_len,
+ const br_rsa_private_key *sk, unsigned char *x);
+
+/**
+ * \brief Get the RSA "i62" implementation (public key operations),
+ * if available.
+ *
+ * \return the implementation, or 0.
+ */
+br_rsa_public br_rsa_i62_public_get(void);
+
+/**
+ * \brief Get the RSA "i62" implementation (PKCS#1 signature verification),
+ * if available.
+ *
+ * \return the implementation, or 0.
+ */
+br_rsa_pkcs1_vrfy br_rsa_i62_pkcs1_vrfy_get(void);
+
+/**
+ * \brief Get the RSA "i62" implementation (private key operations),
+ * if available.
+ *
+ * \return the implementation, or 0.
+ */
+br_rsa_private br_rsa_i62_private_get(void);
+
+/**
+ * \brief Get the RSA "i62" implementation (PKCS#1 signature generation),
+ * if available.
+ *
+ * \return the implementation, or 0.
+ */
+br_rsa_pkcs1_sign br_rsa_i62_pkcs1_sign_get(void);
+
+/*
+ * RSA "i15" engine. Integers are represented as 15-bit integers, so
+ * the code uses only 32-bit multiplication (no 64-bit result), which
+ * is vastly faster (and constant-time) on the ARM Cortex M0/M0+.
+ */
+
+/**
+ * \brief RSA public key engine "i15".
+ *
+ * \see br_rsa_public
+ *
+ * \param x operand to exponentiate.
+ * \param xlen length of the operand (in bytes).
+ * \param pk RSA public key.
+ * \return 1 on success, 0 on error.
+ */
+uint32_t br_rsa_i15_public(unsigned char *x, size_t xlen,
+ const br_rsa_public_key *pk);
+
+/**
+ * \brief RSA signature verification engine "i15".
+ *
+ * \see br_rsa_pkcs1_vrfy
+ *
+ * \param x signature buffer.
+ * \param xlen signature length (in bytes).
+ * \param hash_oid encoded hash algorithm OID (or `NULL`).
+ * \param hash_len expected hash value length (in bytes).
+ * \param pk RSA public key.
+ * \param hash_out output buffer for the hash value.
+ * \return 1 on success, 0 on error.
+ */
+uint32_t br_rsa_i15_pkcs1_vrfy(const unsigned char *x, size_t xlen,
+ const unsigned char *hash_oid, size_t hash_len,
+ const br_rsa_public_key *pk, unsigned char *hash_out);
+
+/**
+ * \brief RSA private key engine "i15".
+ *
+ * \see br_rsa_private
+ *
+ * \param x operand to exponentiate.
+ * \param sk RSA private key.
+ * \return 1 on success, 0 on error.
+ */
+uint32_t br_rsa_i15_private(unsigned char *x,
+ const br_rsa_private_key *sk);
+
+/**
+ * \brief RSA signature generation engine "i15".
+ *
+ * \see br_rsa_pkcs1_sign
+ *
+ * \param hash_oid encoded hash algorithm OID (or `NULL`).
+ * \param hash hash value.
+ * \param hash_len hash value length (in bytes).
+ * \param sk RSA private key.
+ * \param x output buffer for the hash value.
+ * \return 1 on success, 0 on error.
+ */
+uint32_t br_rsa_i15_pkcs1_sign(const unsigned char *hash_oid,
+ const unsigned char *hash, size_t hash_len,
+ const br_rsa_private_key *sk, unsigned char *x);
+
+/**
+ * \brief Get "default" RSA implementation (public-key operations).
+ *
+ * This returns the preferred implementation of RSA (public-key operations)
+ * on the current system.
+ *
+ * \return the default implementation.
+ */
+br_rsa_public br_rsa_public_get_default(void);
+
+/**
+ * \brief Get "default" RSA implementation (private-key operations).
+ *
+ * This returns the preferred implementation of RSA (private-key operations)
+ * on the current system.
+ *
+ * \return the default implementation.
+ */
+br_rsa_private br_rsa_private_get_default(void);
+
+/**
+ * \brief Get "default" RSA implementation (PKCS#1 signature verification).
+ *
+ * This returns the preferred implementation of RSA (signature verification)
+ * on the current system.
+ *
+ * \return the default implementation.
+ */
+br_rsa_pkcs1_vrfy br_rsa_pkcs1_vrfy_get_default(void);
+
+/**
+ * \brief Get "default" RSA implementation (PKCS#1 signature generation).
+ *
+ * This returns the preferred implementation of RSA (signature generation)
+ * on the current system.
+ *
+ * \return the default implementation.
+ */
+br_rsa_pkcs1_sign br_rsa_pkcs1_sign_get_default(void);
+
+/**
+ * \brief RSA decryption helper, for SSL/TLS.
+ *
+ * This function performs the RSA decryption for a RSA-based key exchange
+ * in a SSL/TLS server. The provided RSA engine is used. The `data`
+ * parameter points to the value to decrypt, of length `len` bytes. On
+ * success, the 48-byte pre-master secret is copied into `data`, starting
+ * at the first byte of that buffer; on error, the contents of `data`
+ * become indeterminate.
+ *
+ * This function first checks that the provided value length (`len`) is
+ * not lower than 59 bytes, and matches the RSA modulus length; if neither
+ * of this property is met, then this function returns 0 and the buffer
+ * is unmodified.
+ *
+ * Otherwise, decryption and then padding verification are performed, both
+ * in constant-time. A decryption error, or a bad padding, or an
+ * incorrect decrypted value length are reported with a returned value of
+ * 0; on success, 1 is returned. The caller (SSL server engine) is supposed
+ * to proceed with a random pre-master secret in case of error.