diff --git a/src/crypto/evp/digestsign.c b/src/crypto/evp/digestsign.c
new file mode 100644
index 0000000..c86b805
--- /dev/null
+++ b/src/crypto/evp/digestsign.c
@@ -0,0 +1,205 @@
+/* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
+ * project 2006.
+ */
+/* ====================================================================
+ * Copyright (c) 2006,2007 The OpenSSL Project.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * 3. All advertising materials mentioning features or use of this
+ *    software must display the following acknowledgment:
+ *    "This product includes software developed by the OpenSSL Project
+ *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
+ *
+ * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
+ *    endorse or promote products derived from this software without
+ *    prior written permission. For written permission, please contact
+ *    licensing@OpenSSL.org.
+ *
+ * 5. Products derived from this software may not be called "OpenSSL"
+ *    nor may "OpenSSL" appear in their names without prior written
+ *    permission of the OpenSSL Project.
+ *
+ * 6. Redistributions of any form whatsoever must retain the following
+ *    acknowledgment:
+ *    "This product includes software developed by the OpenSSL Project
+ *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
+ * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
+ * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ * ====================================================================
+ *
+ * This product includes cryptographic software written by Eric Young
+ * (eay@cryptsoft.com).  This product includes software written by Tim
+ * Hudson (tjh@cryptsoft.com). */
+
+#include <openssl/evp.h>
+
+#include <openssl/digest.h>
+#include <openssl/err.h>
+
+#include "internal.h"
+#include "../digest/internal.h"
+
+
+/* md_begin_digset is a callback from the |EVP_MD_CTX| code that is called when
+ * a new digest is begun. */
+static int md_begin_digest(EVP_MD_CTX *ctx) {
+  int r = EVP_PKEY_CTX_ctrl(ctx->pctx, -1, EVP_PKEY_OP_TYPE_SIG,
+                            EVP_PKEY_CTRL_DIGESTINIT, 0, ctx);
+  return r > 0 || r == -2;
+}
+
+static const struct evp_md_pctx_ops md_pctx_ops = {
+  EVP_PKEY_CTX_free,
+  EVP_PKEY_CTX_dup,
+  md_begin_digest,
+};
+
+static int do_sigver_init(EVP_MD_CTX *ctx, EVP_PKEY_CTX **pctx,
+                          const EVP_MD *type, ENGINE *e, EVP_PKEY *pkey,
+                          int is_verify) {
+  if (ctx->pctx == NULL) {
+    ctx->pctx = EVP_PKEY_CTX_new(pkey, e);
+  }
+  if (ctx->pctx == NULL) {
+    return 0;
+  }
+  ctx->pctx_ops = &md_pctx_ops;
+
+  if (type == NULL) {
+    type = EVP_sha1();
+  }
+
+  if (type == NULL) {
+    OPENSSL_PUT_ERROR(EVP, do_sigver_init, EVP_R_NO_DEFAULT_DIGEST);
+    return 0;
+  }
+
+  if (is_verify) {
+    if (ctx->pctx->pmeth->verifyctx_init) {
+      if (ctx->pctx->pmeth->verifyctx_init(ctx->pctx, ctx) <= 0) {
+        return 0;
+      }
+      ctx->pctx->operation = EVP_PKEY_OP_VERIFYCTX;
+    } else if (EVP_PKEY_verify_init(ctx->pctx) <= 0) {
+      return 0;
+    }
+  } else {
+    if (ctx->pctx->pmeth->signctx_init) {
+      if (ctx->pctx->pmeth->signctx_init(ctx->pctx, ctx) <= 0) {
+        return 0;
+      }
+      ctx->pctx->operation = EVP_PKEY_OP_SIGNCTX;
+    } else if (EVP_PKEY_sign_init(ctx->pctx) <= 0) {
+      return 0;
+    }
+  }
+  if (EVP_PKEY_CTX_set_signature_md(ctx->pctx, type) <= 0) {
+    return 0;
+  }
+  if (pctx) {
+    *pctx = ctx->pctx;
+  }
+  if (!EVP_DigestInit_ex(ctx, type, e)) {
+    return 0;
+  }
+  return 1;
+}
+
+int EVP_DigestSignInit(EVP_MD_CTX *ctx, EVP_PKEY_CTX **pctx, const EVP_MD *type,
+                       ENGINE *e, EVP_PKEY *pkey) {
+  return do_sigver_init(ctx, pctx, type, e, pkey, 0);
+}
+
+int EVP_DigestVerifyInit(EVP_MD_CTX *ctx, EVP_PKEY_CTX **pctx,
+                         const EVP_MD *type, ENGINE *e, EVP_PKEY *pkey) {
+  return do_sigver_init(ctx, pctx, type, e, pkey, 1);
+}
+
+int EVP_DigestSignUpdate(EVP_MD_CTX *ctx, const void *data, size_t len) {
+  return EVP_DigestUpdate(ctx, data, len);
+}
+
+int EVP_DigestVerifyUpdate(EVP_MD_CTX *ctx, const void *data, size_t len) {
+  return EVP_DigestUpdate(ctx, data, len);
+}
+
+int EVP_DigestSignFinal(EVP_MD_CTX *ctx, uint8_t *out_sig,
+                        size_t *out_sig_len) {
+  int r = 0;
+  const int has_signctx = ctx->pctx->pmeth->signctx != NULL;
+
+  if (out_sig) {
+    EVP_MD_CTX tmp_ctx;
+    uint8_t md[EVP_MAX_MD_SIZE];
+    unsigned int mdlen;
+
+    EVP_MD_CTX_init(&tmp_ctx);
+    if (!EVP_MD_CTX_copy_ex(&tmp_ctx, ctx)) {
+      return 0;
+    }
+    if (has_signctx) {
+      r = tmp_ctx.pctx->pmeth->signctx(tmp_ctx.pctx, out_sig, out_sig_len, &tmp_ctx);
+    } else {
+      r = EVP_DigestFinal_ex(&tmp_ctx, md, &mdlen);
+    }
+    EVP_MD_CTX_cleanup(&tmp_ctx);
+    if (has_signctx || !r) {
+      return r;
+    }
+    return EVP_PKEY_sign(ctx->pctx, out_sig, out_sig_len, md, mdlen);
+  } else {
+    if (has_signctx) {
+      return ctx->pctx->pmeth->signctx(ctx->pctx, out_sig, out_sig_len, ctx);
+    } else {
+      size_t s = EVP_MD_size(ctx->digest);
+      return EVP_PKEY_sign(ctx->pctx, out_sig, out_sig_len, NULL, s);
+    }
+  }
+}
+
+int EVP_DigestVerifyFinal(EVP_MD_CTX *ctx, const uint8_t *sig,
+                          size_t sig_len) {
+  EVP_MD_CTX tmp_ctx;
+  uint8_t md[EVP_MAX_MD_SIZE];
+  int r;
+  unsigned int mdlen;
+  const int has_verifyctx = ctx->pctx->pmeth->verifyctx != NULL;
+
+  EVP_MD_CTX_init(&tmp_ctx);
+  if (!EVP_MD_CTX_copy_ex(&tmp_ctx, ctx)) {
+    return 0;
+  }
+  if (has_verifyctx) {
+    r = tmp_ctx.pctx->pmeth->verifyctx(tmp_ctx.pctx, sig, sig_len, &tmp_ctx);
+  } else {
+    r = EVP_DigestFinal_ex(&tmp_ctx, md, &mdlen);
+  }
+
+  EVP_MD_CTX_cleanup(&tmp_ctx);
+  if (has_verifyctx || !r) {
+    return r;
+  }
+  return EVP_PKEY_verify(ctx->pctx, sig, sig_len, md, mdlen);
+}