implement hashlib.new('sha256') support

Author: samblenny

py/circuitpy_mpconfig.mk

@@ -343,6 +343,9 @@ CFLAGS += -DCIRCUITPY_HASHLIB_MBEDTLS=$(CIRCUITPY_HASHLIB_MBEDTLS)
 CIRCUITPY_HASHLIB_MBEDTLS_ONLY ?= $(call enable-if-all,$(CIRCUITPY_HASHLIB_MBEDTLS) $(call enable-if-not,$(CIRCUITPY_SSL)))
 CFLAGS += -DCIRCUITPY_HASHLIB_MBEDTLS_ONLY=$(CIRCUITPY_HASHLIB_MBEDTLS_ONLY)
 
+CIRCUITPY_HASHLIB_SHA256 ?= 0
+CFLAGS += -DCIRCUITPY_HASHLIB_SHA256=$(CIRCUITPY_HASHLIB_SHA256)
+
 CIRCUITPY_I2CTARGET ?= $(CIRCUITPY_FULL_BUILD)
 CFLAGS += -DCIRCUITPY_I2CTARGET=$(CIRCUITPY_I2CTARGET)
 

shared-module/hashlib/Hash.c

@@ -14,6 +14,12 @@ void common_hal_hashlib_hash_update(hashlib_hash_obj_t *self, const uint8_t *dat
         mbedtls_sha1_update_ret(&self->sha1, data, datalen);
         return;
     }
+    #if CIRCUITPY_HASHLIB_SHA256
+    else if (self->hash_type == MBEDTLS_SSL_HASH_SHA256) {
+        mbedtls_sha256_update_ret(&self->sha256, data, datalen);
+        return;
+    }
+    #endif
 }
 
 void common_hal_hashlib_hash_digest(hashlib_hash_obj_t *self, uint8_t *data, size_t datalen) {
@@ -28,11 +34,25 @@ void common_hal_hashlib_hash_digest(hashlib_hash_obj_t *self, uint8_t *data, siz
         mbedtls_sha1_finish_ret(&self->sha1, data);
         mbedtls_sha1_clone(&self->sha1, &copy);
     }
+    #if CIRCUITPY_HASHLIB_SHA256
+    else if (self->hash_type == MBEDTLS_SSL_HASH_SHA256) {
+        mbedtls_sha256_context copy;
+        mbedtls_sha256_clone(&copy, &self->sha256);
+        mbedtls_sha256_finish_ret(&self->sha256, data);
+        mbedtls_sha256_clone(&self->sha256, &copy);
+    }
+    #endif
 }
 
 size_t common_hal_hashlib_hash_get_digest_size(hashlib_hash_obj_t *self) {
     if (self->hash_type == MBEDTLS_SSL_HASH_SHA1) {
         return 20;
     }
+    #if CIRCUITPY_HASHLIB_SHA256
+    else if (self->hash_type == MBEDTLS_SSL_HASH_SHA256) {
+        return 32;
+    }
+    #endif
+
     return 0;
 }

shared-module/hashlib/Hash.h

@@ -7,11 +7,17 @@
 #pragma once
 
 #include "mbedtls/sha1.h"
+#if CIRCUITPY_HASHLIB_SHA256
+#include "mbedtls/sha256.h"
+#endif
 
 typedef struct {
     mp_obj_base_t base;
     union {
         mbedtls_sha1_context sha1;
+        #if CIRCUITPY_HASHLIB_SHA256
+        mbedtls_sha256_context sha256;
+        #endif
     };
     // Of MBEDTLS_SSL_HASH_*
     uint8_t hash_type;

shared-module/hashlib/__init__.c

@@ -17,5 +17,13 @@ bool common_hal_hashlib_new(hashlib_hash_obj_t *self, const char *algorithm) {
         mbedtls_sha1_starts_ret(&self->sha1);
         return true;
     }
+    #if CIRCUITPY_HASHLIB_SHA256
+    else if (strcmp(algorithm, "sha256") == 0) {
+        self->hash_type = MBEDTLS_SSL_HASH_SHA256;
+        mbedtls_sha256_init(&self->sha256);
+        mbedtls_sha256_starts_ret(&self->sha256, 0);
+        return true;
+    }
+    #endif
     return false;
 }

shared-module/hashlib/__init__.h

@@ -13,4 +13,11 @@
 #define mbedtls_sha1_starts_ret mbedtls_sha1_starts
 #define mbedtls_sha1_update_ret mbedtls_sha1_update
 #define mbedtls_sha1_finish_ret mbedtls_sha1_finish
+
+#if CIRCUITPY_HASHLIB_SHA256
+#define mbedtls_sha256_starts_ret mbedtls_sha256_starts
+#define mbedtls_sha256_update_ret mbedtls_sha256_update
+#define mbedtls_sha256_finish_ret mbedtls_sha256_finish
+#endif
+
 #endif