diff --git a/include/polarssl/config.h b/include/polarssl/config.h
index 119dc67ea..84b36b63f 100644
--- a/include/polarssl/config.h
+++ b/include/polarssl/config.h
@@ -844,7 +844,7 @@
  * Module:  library/ecdsa.c
  * Caller:
  *
- * Requires: POLARSSL_ECP_C
+ * Requires: POLARSSL_ECP_C, POLARSSL_ASN1_WRITE_C, POLARSSL_ASN1_PARSE_C
  */
 #define POLARSSL_ECDSA_C
 
@@ -1371,7 +1371,10 @@
 #error "POLARSSL_ECDH_C defined, but not all prerequisites"
 #endif
 
-#if defined(POLARSSL_ECDSA_C) && !defined(POLARSSL_ECP_C)
+#if defined(POLARSSL_ECDSA_C) &&            \
+    ( !defined(POLARSSL_ECP_C) ||           \
+      !defined(POLARSSL_ASN1_PARSE_C) ||    \
+      !defined(POLARSSL_ASN1_WRITE_C) )
 #error "POLARSSL_ECDSA_C defined, but not all prerequisites"
 #endif
 
diff --git a/include/polarssl/ecdsa.h b/include/polarssl/ecdsa.h
index bc1afbbed..d61e82c2d 100644
--- a/include/polarssl/ecdsa.h
+++ b/include/polarssl/ecdsa.h
@@ -83,6 +83,63 @@ int ecdsa_verify( const ecp_group *grp,
                   const unsigned char *buf, size_t blen,
                   const ecp_point *Q, const mpi *r, const mpi *s);
 
+/**
+ * \brief           Compute ECDSA signature and write it to buffer,
+ *                  serialized as defined in RFC 4492 page 20.
+ *
+ * \param ctx       ECDSA context
+ * \param hash      Message hash
+ * \param hlen      Length of hash
+ * \param sig       Buffer that will hold the signature
+ * \param slen      Length of the signature written
+ * \param f_rng     RNG function
+ * \param p_rng     RNG parameter
+ *
+ * \note            The "sig" buffer must be at least as large as twice the
+ *                  size of the curve used, plus 7 (eg. 71 bytes if a 256-bit
+ *                  curve is used).
+ *
+ * \return          0 if successful,
+ *                  or a POLARSSL_ERR_ECP, POLARSSL_ERR_MPI or
+ *                  POLARSSL_ERR_ASN1 error code
+ */
+int ecdsa_write_signature( ecdsa_context *ctx,
+                           const unsigned char *hash, size_t hlen,
+                           unsigned char *sig, size_t *slen,
+                           int (*f_rng)(void *, unsigned char *, size_t),
+                           void *p_rng );
+
+/**
+ * \brief           Read and verify an ECDSA signature
+ *
+ * \param ctx       ECDSA context
+ * \param hash      Message hash
+ * \param hlen      Size of hash
+ * \param sig       Signature to read and verify
+ * \param slen      Size of sig
+ *
+ * \return          0 if successful,
+ *                  POLARSSL_ERR_ECP_BAD_INPUT_DATA if signature is invalid
+ *                  or a POLARSSL_ERR_ECP or POLARSSL_ERR_MPI error code
+ */
+int ecdsa_read_signature( ecdsa_context *ctx,
+                          const unsigned char *hash, size_t hlen,
+                          const unsigned char *sig, size_t slen );
+
+/**
+ * \brief           Generate an ECDSA keypair on the given curve
+ *
+ * \param ctx       ECDSA context in which the keypair should be stored
+ * \param grp       Group (elliptic curve) to use. One of the various
+ *                  POLARSSL_ECP_DP_XXX macros depending on configuration.
+ * \param f_rng     RNG function
+ * \param p_rng     RNG parameter
+ *
+ * \return          0 on success, or a POLARSSL_ERR_ECP code.
+ */
+int ecdsa_genkey( ecdsa_context *ctx, ecp_group_id gid,
+                  int (*f_rng)(void *, unsigned char *, size_t), void *p_rng );
+
 /**
  * \brief           Initialize context
  *
diff --git a/include/polarssl/ecp.h b/include/polarssl/ecp.h
index 7bd9bd587..2082bd960 100644
--- a/include/polarssl/ecp.h
+++ b/include/polarssl/ecp.h
@@ -126,9 +126,10 @@ ecp_keypair;
 #define POLARSSL_ECP_DP_SECP521R1   25
 
 /**
- * Maximum bit size of the groups (that is, of N)
+ * Maximum size of the groups (that is, of N and P)
  */
-#define POLARSSL_ECP_MAX_N_BITS     521
+#define POLARSSL_ECP_MAX_BITS     521
+#define POLARSSL_ECP_MAX_BYTES    ( ( POLARSSL_ECP_MAX_BITS + 7 ) / 8 )
 
 /*
  * Maximum window size (actually, NAF width) used for point multipliation.
@@ -218,6 +219,17 @@ int ecp_is_zero( ecp_point *pt );
  */
 int ecp_copy( ecp_point *P, const ecp_point *Q );
 
+/**
+ * \brief           Copy the contents of a group object
+ *
+ * \param dst       Destination group
+ * \param src       Source group
+ *
+ * \return          0 if successful,
+ *                  POLARSSL_ERR_MPI_MALLOC_FAILED if memory allocation failed
+ */
+int ecp_group_copy( ecp_group *dst, const ecp_group *src );
+
 /**
  * \brief           Import a non-zero point from two ASCII strings
  *
diff --git a/library/ecdsa.c b/library/ecdsa.c
index e87bc6527..6746233b4 100644
--- a/library/ecdsa.c
+++ b/library/ecdsa.c
@@ -34,6 +34,7 @@
 #if defined(POLARSSL_ECDSA_C)
 
 #include "polarssl/ecdsa.h"
+#include "polarssl/asn1write.h"
 
 /*
  * Derive a suitable integer for group grp from a buffer of length len
@@ -187,6 +188,102 @@ cleanup:
     return( ret );
 }
 
+/*
+ * RFC 4492 page 20:
+ *
+ *     Ecdsa-Sig-Value ::= SEQUENCE {
+ *         r       INTEGER,
+ *         s       INTEGER
+ *     }
+ *
+ * Size is at most
+ *    1 (tag) + 1 (len) + 1 (initial 0) + ECP_MAX_BYTES for each of r and s,
+ *    twice that + 1 (tag) + 2 (len) for the sequence
+ * (assuming ECP_MAX_BYTES is less than 126 for r and s,
+ * and less than 124 (total len <= 255) for the sequence)
+ */
+#if POLARSSL_ECP_MAX_BYTES > 124
+#error "POLARSSL_ECP_MAX_BYTES bigger than expected, please fix MAX_SIG_LEN"
+#endif
+#define MAX_SIG_LEN ( 3 + 2 * ( 2 + POLARSSL_ECP_MAX_BYTES ) )
+
+/*
+ * Compute and write signature
+ */
+int ecdsa_write_signature( ecdsa_context *ctx,
+                           const unsigned char *hash, size_t hlen,
+                           unsigned char *sig, size_t *slen,
+                           int (*f_rng)(void *, unsigned char *, size_t),
+                           void *p_rng )
+{
+    int ret;
+    unsigned char buf[MAX_SIG_LEN];
+    unsigned char *p = buf + MAX_SIG_LEN - 1;
+    size_t len = 0;
+
+    if( ( ret = ecdsa_sign( &ctx->grp, &ctx->r, &ctx->s, &ctx->d,
+                            hash, hlen, f_rng, p_rng ) ) != 0 )
+    {
+        return( ret );
+    }
+
+    ASN1_CHK_ADD( len, asn1_write_mpi( &p, buf, &ctx->s ) );
+    ASN1_CHK_ADD( len, asn1_write_mpi( &p, buf, &ctx->r ) );
+
+    ASN1_CHK_ADD( len, asn1_write_len( &p, buf, len ) );
+    ASN1_CHK_ADD( len, asn1_write_tag( &p, buf,
+                                       ASN1_CONSTRUCTED | ASN1_SEQUENCE ) );
+
+    memcpy( sig, p, len );
+    *slen = len;
+
+    return( 0 );
+}
+
+/*
+ * Read and check signature
+ */
+int ecdsa_read_signature( ecdsa_context *ctx,
+                          const unsigned char *hash, size_t hlen,
+                          const unsigned char *sig, size_t slen )
+{
+    int ret;
+    unsigned char *p = (unsigned char *) sig;
+    const unsigned char *end = sig + slen;
+    size_t len;
+
+    if( ( ret = asn1_get_tag( &p, end, &len,
+                    ASN1_CONSTRUCTED | ASN1_SEQUENCE ) ) != 0 )
+    {
+        return( POLARSSL_ERR_ECP_BAD_INPUT_DATA + ret );
+    }
+
+    if( p + len != end )
+        return( POLARSSL_ERR_ECP_BAD_INPUT_DATA +
+                POLARSSL_ERR_ASN1_LENGTH_MISMATCH );
+
+    if( ( ret = asn1_get_mpi( &p, end, &ctx->r ) ) != 0 ||
+        ( ret = asn1_get_mpi( &p, end, &ctx->s ) ) != 0 )
+        return( POLARSSL_ERR_ECP_BAD_INPUT_DATA + ret );
+
+    if( p != end )
+        return( POLARSSL_ERR_ECP_BAD_INPUT_DATA +
+                POLARSSL_ERR_ASN1_LENGTH_MISMATCH );
+
+    return( ecdsa_verify( &ctx->grp, hash, hlen, &ctx->Q, &ctx->r, &ctx->s ) );
+}
+
+/*
+ * Generate key pair
+ */
+int ecdsa_genkey( ecdsa_context *ctx, ecp_group_id gid,
+                  int (*f_rng)(void *, unsigned char *, size_t), void *p_rng )
+{
+    return( ecp_use_known_dp( &ctx->grp, gid ) ||
+            ecp_gen_keypair( &ctx->grp, &ctx->d, &ctx->Q, f_rng, p_rng ) );
+}
+
+
 /*
  * Initialize context
  */
diff --git a/library/ecp.c b/library/ecp.c
index 14683120a..09a021bf8 100644
--- a/library/ecp.c
+++ b/library/ecp.c
@@ -181,6 +181,14 @@ cleanup:
     return( ret );
 }
 
+/*
+ * Copy the contents of a group object
+ */
+int ecp_group_copy( ecp_group *dst, const ecp_group *src )
+{
+    return ecp_use_known_dp( dst, src->id );
+}
+
 /*
  * Import a non-zero point from ASCII strings
  */
@@ -1146,7 +1154,7 @@ cleanup:
  * (that is: grp->nbits / w + 1)
  * Allow p_bits + 1 bits in case M = grp->N + 1 is one bit longer than N.
  */
-#define MAX_NAF_LEN     ( POLARSSL_ECP_MAX_N_BITS / 2 + 1 )
+#define MAX_NAF_LEN     ( POLARSSL_ECP_MAX_BITS / 2 + 1 )
 
 /*
  * Integer multiplication: R = m * P
diff --git a/programs/.gitignore b/programs/.gitignore
index 9a6953247..e9f4e54ef 100644
--- a/programs/.gitignore
+++ b/programs/.gitignore
@@ -9,6 +9,7 @@ hash/sha2sum
 pkey/dh_client
 pkey/dh_genprime
 pkey/dh_server
+pkey/ecdsa
 pkey/key_app
 pkey/key_app_writer
 pkey/mpi_demo
diff --git a/programs/Makefile b/programs/Makefile
index 388b029e2..1c2b5fc80 100644
--- a/programs/Makefile
+++ b/programs/Makefile
@@ -91,6 +91,10 @@ pkey/dh_server: pkey/dh_server.c ../library/libpolarssl.a
 	echo   "  CC    pkey/dh_server.c"
 	$(CC) $(CFLAGS) $(OFLAGS) pkey/dh_server.c   $(LDFLAGS) -o $@
 
+pkey/ecdsa: pkey/ecdsa.c ../library/libpolarssl.a
+	echo   "  CC    pkey/ecdsa.c"
+	$(CC) $(CFLAGS) $(OFLAGS) pkey/ecdsa.c       $(LDFLAGS) -o $@
+
 pkey/key_app: pkey/key_app.c ../library/libpolarssl.a
 	echo   "  CC    pkey/key_app.c"
 	$(CC) $(CFLAGS) $(OFLAGS) pkey/key_app.c   $(LDFLAGS) -o $@
diff --git a/programs/pkey/CMakeLists.txt b/programs/pkey/CMakeLists.txt
index c8551a623..015505b65 100644
--- a/programs/pkey/CMakeLists.txt
+++ b/programs/pkey/CMakeLists.txt
@@ -7,6 +7,9 @@ target_link_libraries(dh_genprime polarssl)
 add_executable(dh_server dh_server.c)
 target_link_libraries(dh_server polarssl)
 
+add_executable(ecdsa ecdsa.c)
+target_link_libraries(ecdsa polarssl)
+
 add_executable(key_app key_app.c)
 target_link_libraries(key_app polarssl)
 
diff --git a/programs/pkey/ecdsa.c b/programs/pkey/ecdsa.c
new file mode 100644
index 000000000..8d52b6726
--- /dev/null
+++ b/programs/pkey/ecdsa.c
@@ -0,0 +1,199 @@
+/*
+ *  Example ECDSA program
+ *
+ *  Copyright (C) 2013, Brainspark B.V.
+ *
+ *  This file is part of PolarSSL (http://www.polarssl.org)
+ *  Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
+ *
+ *  All rights reserved.
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "polarssl/config.h"
+
+#include "polarssl/entropy.h"
+#include "polarssl/ctr_drbg.h"
+#include "polarssl/ecdsa.h"
+
+#include <string.h>
+#include <stdio.h>
+
+/*
+ * Uncomment to force use of a specific curve
+#define ECPARAMS    POLARSSL_ECP_DP_SECP256R1
+ */
+
+#if !defined(ECPARAMS)
+#if defined(POLARSSL_ECP_DP_SECP192R1_ENABLED)
+#define ECPARAMS    POLARSSL_ECP_DP_SECP192R1
+#elif defined(POLARSSL_ECP_DP_SECP224R1_ENABLED)
+#define ECPARAMS    POLARSSL_ECP_DP_SECP224R1
+#elif defined(POLARSSL_ECP_DP_SECP256R1_ENABLED)
+#define ECPARAMS    POLARSSL_ECP_DP_SECP256R1
+#elif defined(POLARSSL_ECP_DP_SECP384R1_ENABLED)
+#define ECPARAMS    POLARSSL_ECP_DP_SECP384R1
+#elif defined(POLARSSL_ECP_DP_SECP521R1_ENABLED)
+#define ECPARAMS    POLARSSL_ECP_DP_SECP521R1
+#endif
+#endif /* !defined(ECPARAMS) */
+
+#if !defined(POLARSSL_BIGNUM_C) || !defined(POLARSSL_ECDSA_C) || \
+    !defined(POLARSSL_ENTROPY_C) || !defined(POLARSSL_CTR_DRBG_C) || \
+    !defined(ECPARAMS)
+int main( int argc, char *argv[] )
+{
+    ((void) argc);
+    ((void) argv);
+
+    printf("POLARSSL_BIGNUM_C and/or POLARSSL_ECDSA_C and/or "
+           "POLARSSL_ENTROPY_C and/or POLARSSL_CTR_DRBG_C not defined,"
+           "and/or not EC domain parameter available\n" );
+    return( 0 );
+}
+#else
+int main( int argc, char *argv[] )
+{
+    int ret;
+    ecdsa_context ctx_sign, ctx_verify;
+    entropy_context entropy;
+    ctr_drbg_context ctr_drbg;
+    unsigned char hash[] = "This should be the hash of a message.";
+    unsigned char sig[512];
+    size_t sig_len;
+    const char *pers = "ecdsa";
+    ((void) argv);
+
+    ecdsa_init( &ctx_sign );
+    ecdsa_init( &ctx_verify );
+
+    memset(sig, 0, sizeof( sig ) );
+    ret = 1;
+
+    if( argc != 1 )
+    {
+        printf( "usage: ecdsa\n" );
+
+#if defined(_WIN32)
+        printf( "\n" );
+#endif
+
+        goto exit;
+    }
+
+    /*
+     * Generate a key pair for signing
+     */
+    printf( "\n  . Seeding the random number generator..." );
+    fflush( stdout );
+
+    entropy_init( &entropy );
+    if( ( ret = ctr_drbg_init( &ctr_drbg, entropy_func, &entropy,
+                               (const unsigned char *) pers,
+                               strlen( pers ) ) ) != 0 )
+    {
+        printf( " failed\n  ! ctr_drbg_init returned %d\n", ret );
+        goto exit;
+    }
+
+    printf( " ok\n  . Generating key pair..." );
+    fflush( stdout );
+
+    if( ( ret = ecdsa_genkey( &ctx_sign, ECPARAMS,
+                              ctr_drbg_random, &ctr_drbg ) ) != 0 )
+    {
+        printf( " failed\n  ! ecdsa_genkey returned %d\n", ret );
+        goto exit;
+    }
+
+    printf( " ok (key size: %d bits)\n", (int) ctx_sign.grp.pbits );
+
+    /*
+     * Sign some message hash
+     */
+    printf( "  . Signing message..." );
+    fflush( stdout );
+
+    if( ( ret = ecdsa_write_signature( &ctx_sign,
+                                       hash, sizeof( hash ),
+                                       sig, &sig_len,
+                                       ctr_drbg_random, &ctr_drbg ) ) != 0 )
+    {
+        printf( " failed\n  ! ecdsa_genkey returned %d\n", ret );
+        goto exit;
+    }
+    printf( " ok\n" );
+
+    /*
+     * Signature is serialized as defined by RFC 4492 p. 20,
+     * but one can also access 'r' and 's' directly from the context
+     */
+#ifdef POLARSSL_FS_IO
+    mpi_write_file( "    r = ", &ctx_sign.r, 16, NULL );
+    mpi_write_file( "    s = ", &ctx_sign.s, 16, NULL );
+#endif
+
+    /*
+     * Transfer public information to verifying context
+     */
+    printf( "  . Preparing verification context..." );
+    fflush( stdout );
+
+    if( ( ret = ecp_group_copy( &ctx_verify.grp, &ctx_sign.grp ) ) != 0 )
+    {
+        printf( " failed\n  ! ecp_group_copy returned %d\n", ret );
+        goto exit;
+    }
+
+    if( ( ret = ecp_copy( &ctx_verify.Q, &ctx_sign.Q ) ) != 0 )
+    {
+        printf( " failed\n  ! ecp_copy returned %d\n", ret );
+        goto exit;
+    }
+
+    ret = 0;
+
+    /*
+     * Verify signature
+     */
+    printf( " ok\n  . Verifying signature..." );
+    fflush( stdout );
+
+    if( ( ret = ecdsa_read_signature( &ctx_verify,
+                                      hash, sizeof( hash ),
+                                      sig, sig_len ) ) != 0 )
+    {
+        printf( " failed\n  ! ecdsa_read_signature returned %d\n", ret );
+        goto exit;
+    }
+
+    printf( " ok\n" );
+
+exit:
+
+#if defined(_WIN32)
+    printf( "  + Press Enter to exit this program.\n" );
+    fflush( stdout ); getchar();
+#endif
+
+    ecdsa_free( &ctx_verify );
+    ecdsa_free( &ctx_sign );
+
+    return( ret );
+}
+#endif /* POLARSSL_BIGNUM_C && POLARSSL_ECDSA_C &&
+          POLARSSL_ENTROPY_C && POLARSSL_CTR_DRBG_C &&
+          ECPARAMS */
diff --git a/tests/suites/test_suite_ecdsa.data b/tests/suites/test_suite_ecdsa.data
index 386c8f43e..886065ff4 100644
--- a/tests/suites/test_suite_ecdsa.data
+++ b/tests/suites/test_suite_ecdsa.data
@@ -22,3 +22,17 @@ ecdsa_prim_test_vectors:POLARSSL_ECP_DP_SECP384R1:"0BEB646634BA87735D77AE4809A0E
 ECDSA primitive rfc 4754 p521
 ecdsa_prim_test_vectors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
 
+ECDSA write-read random #1
+ecdsa_write_read_random:POLARSSL_ECP_DP_SECP192R1
+
+ECDSA write-read random #2
+ecdsa_write_read_random:POLARSSL_ECP_DP_SECP224R1
+
+ECDSA write-read random #3
+ecdsa_write_read_random:POLARSSL_ECP_DP_SECP256R1
+
+ECDSA write-read random #4
+ecdsa_write_read_random:POLARSSL_ECP_DP_SECP384R1
+
+ECDSA write-read random #5
+ecdsa_write_read_random:POLARSSL_ECP_DP_SECP521R1
diff --git a/tests/suites/test_suite_ecdsa.function b/tests/suites/test_suite_ecdsa.function
index 5e1ba6431..b4d6ffdc6 100644
--- a/tests/suites/test_suite_ecdsa.function
+++ b/tests/suites/test_suite_ecdsa.function
@@ -76,3 +76,61 @@ void ecdsa_prim_test_vectors( int id, char *d_str, char *xQ_str, char *yQ_str,
     mpi_free( &r_check ); mpi_free( &s_check );
 }
 /* END_CASE */
+
+/* BEGIN_CASE */
+void ecdsa_write_read_random( int id )
+{
+    ecdsa_context ctx;
+    rnd_pseudo_info rnd_info;
+    unsigned char hash[66];
+    unsigned char sig[200];
+    size_t sig_len, i;
+
+    ecdsa_init( &ctx );
+    memset( &rnd_info, 0x00, sizeof( rnd_pseudo_info ) );
+    memset( hash, 0, sizeof( hash ) );
+    memset( sig, 0x2a, sizeof( sig ) );
+
+    /* prepare material for signature */
+    TEST_ASSERT( rnd_pseudo_rand( &rnd_info, hash, sizeof( hash ) ) == 0 );
+
+    /* generate signing key */
+    TEST_ASSERT( ecdsa_genkey( &ctx, id, &rnd_pseudo_rand, &rnd_info ) == 0 );
+
+    /* generate and write signature, then read and verify it */
+    TEST_ASSERT( ecdsa_write_signature( &ctx, hash, sizeof( hash ),
+                 sig, &sig_len, &rnd_pseudo_rand, &rnd_info ) == 0 );
+    TEST_ASSERT( ecdsa_read_signature( &ctx, hash, sizeof( hash ),
+                 sig, sig_len ) == 0 );
+
+    /* check we didn't write past the announced length */
+    for( i = sig_len; i < sizeof( sig ); i++ )
+        TEST_ASSERT( sig[i] == 0x2a );
+
+    /* try verification with invalid length */
+    TEST_ASSERT( ecdsa_read_signature( &ctx, hash, sizeof( hash ),
+                 sig, sig_len - 1 ) != 0 );
+    TEST_ASSERT( ecdsa_read_signature( &ctx, hash, sizeof( hash ),
+                 sig, sig_len + 1 ) != 0 );
+
+    /* try invalid sequence tag */
+    sig[0]++;
+    TEST_ASSERT( ecdsa_read_signature( &ctx, hash, sizeof( hash ),
+                 sig, sig_len ) != 0 );
+    sig[0]--;
+
+    /* try modifying r */
+    sig[10]++;
+    TEST_ASSERT( ecdsa_read_signature( &ctx, hash, sizeof( hash ),
+                 sig, sig_len ) != 0 );
+    sig[10]--;
+
+    /* try modifying s */
+    sig[sig_len - 1]++;
+    TEST_ASSERT( ecdsa_read_signature( &ctx, hash, sizeof( hash ),
+                 sig, sig_len ) != 0 );
+    sig[sig_len - 1]--;
+
+    ecdsa_free( &ctx );
+}
+/* END_CASE */