diff --git a/include/secp256k1.h b/include/secp256k1.h
index e9944e5..369a95e 100644
--- a/include/secp256k1.h
+++ b/include/secp256k1.h
@@ -27,18 +27,33 @@ int secp256k1_ecdsa_verify(const unsigned char *msg, int msglen,
                            const unsigned char *sig, int siglen,
                            const unsigned char *pubkey, int pubkeylen);
 
+/** Create an ECDSA signature.
+ *  Returns: 1: signature created
+ *           0: nonce invalid, try another one
+ *  In:      msg:    the message being signed
+ *           msglen: the length of the message being signed
+ *           seckey: pointer to a 32-byte secret key (assumed to be valid)
+ *           nonce:  pointer to a 32-byte nonce (generated with a cryptographic PRNG)
+ *  Out:     sig:    pointer to a 72-byte array where the signature will be placed.
+ *           siglen: pointer to an int, which will be updated to the signature length (<=72).
+ */
 int secp256k1_ecdsa_sign(const unsigned char *msg, int msglen,
-                         unsigned char *sig, int* siglen,
+                         unsigned char *sig, int *siglen,
                          const unsigned char *seckey,
                          const unsigned char *nonce);
 
+
+/** Verify an ECDSA secret key.
+ *  Returns: 1: secret key is valid
+ *           0: secret key is invalid
+ *  In:      seckey: pointer to a 32-byte secret key
+ */
 int secp256j1_ecdsa_seckey_verify(const unsigned char *seckey);
 
 /** Just validate a public key.
  *  Returns: 1: valid public key
  *           0: invalid public key
  */
-/* NOT YET IMPLEMENTED */
 int secp256k1_ecdsa_pubkey_verify(const unsigned char *pubkey, int pubkeylen);
 
 /** Compute the public key for a secret key.
@@ -51,8 +66,7 @@ int secp256k1_ecdsa_pubkey_verify(const unsigned char *pubkey, int pubkeylen);
  *  Returns: 1: secret was valid, public key stores
  *           0: secret was invalid, try again.
  */
-/* NOT YET IMPLEMENTED */
-int secp256k1_ecdsa_pubkey_create(unsigned char *pubkey, int *pubkeylen, const unsigned char *seckey, int compressed)
+int secp256k1_ecdsa_pubkey_create(unsigned char *pubkey, int *pubkeylen, const unsigned char *seckey, int compressed);
 
 int secp256k1_ecdsa_pubkey_decompress(unsigned char *pubkey, int *pubkeylen);
 
diff --git a/src/ecdsa.h b/src/ecdsa.h
index f6f3642..5ddbf65 100644
--- a/src/ecdsa.h
+++ b/src/ecdsa.h
@@ -11,6 +11,7 @@ void static secp256k1_ecdsa_sig_init(secp256k1_ecdsa_sig_t *r);
 void static secp256k1_ecdsa_sig_free(secp256k1_ecdsa_sig_t *r);
 
 int static secp256k1_ecdsa_pubkey_parse(secp256k1_gej_t *elem, const unsigned char *pub, int size);
+void static secp256k1_ecdsa_pubkey_serialize(secp256k1_ge_t *elem, unsigned char *pub, int *size, int compressed);
 int static secp256k1_ecdsa_sig_parse(secp256k1_ecdsa_sig_t *r, const unsigned char *sig, int size);
 int static secp256k1_ecdsa_sig_serialize(unsigned char *sig, int *size, const secp256k1_ecdsa_sig_t *a);
 int static secp256k1_ecdsa_sig_verify(const secp256k1_ecdsa_sig_t *sig, const secp256k1_gej_t *pubkey, const secp256k1_num_t *message);
diff --git a/src/impl/ecdsa.h b/src/impl/ecdsa.h
index 1e98a75..e7dfba4 100644
--- a/src/impl/ecdsa.h
+++ b/src/impl/ecdsa.h
@@ -146,4 +146,18 @@ void static secp256k1_ecdsa_sig_set_rs(secp256k1_ecdsa_sig_t *sig, const secp256
     secp256k1_num_copy(&sig->s, s);
 }
 
+void static secp256k1_ecdsa_pubkey_serialize(secp256k1_ge_t *elem, unsigned char *pub, int *size, int compressed) {
+    secp256k1_fe_normalize(&elem->x);
+    secp256k1_fe_normalize(&elem->y);
+    secp256k1_fe_get_b32(&pub[1], &elem->x);
+    if (compressed) {
+        *size = 33;
+        pub[0] = 0x02 | (secp256k1_fe_is_odd(&elem->y) ? 0x01 : 0x00);
+    } else {
+        *size = 65;
+        pub[0] = 0x04;
+        secp256k1_fe_get_b32(&pub[33], &elem->y);
+    }
+}
+
 #endif
diff --git a/src/secp256k1.c b/src/secp256k1.c
index abe1df4..be896a9 100644
--- a/src/secp256k1.c
+++ b/src/secp256k1.c
@@ -64,3 +64,40 @@ int secp256k1_ecdsa_sign(const unsigned char *message, int messagelen, unsigned
     secp256k1_num_free(&sec);
     return ret;
 }
+
+int secp256k1_ecdsa_seckey_verify(const unsigned char *seckey) {
+    secp256k1_num_t sec;
+    secp256k1_num_init(&sec);
+    secp256k1_num_set_bin(&sec, seckey, 32);
+    int ret = secp256k1_num_is_zero(&sec) ||
+              (secp256k1_num_cmp(&sec, &secp256k1_ge_consts->order) >= 0);
+    secp256k1_num_free(&sec);
+    return ret;
+}
+
+int secp256k1_ecdsa_pubkey_verify(const unsigned char *pubkey, int pubkeylen) {
+    secp256k1_gej_t q;
+    return secp256k1_ecdsa_pubkey_parse(&q, pubkey, pubkeylen);
+}
+
+int secp256k1_ecdsa_pubkey_create(unsigned char *pubkey, int *pubkeylen, const unsigned char *seckey, int compressed) {
+    secp256k1_num_t sec;
+    secp256k1_num_init(&sec);
+    secp256k1_num_set_bin(&sec, seckey, 32);
+    secp256k1_gej_t pj;
+    secp256k1_ecmult_gen(&pj, &sec);
+    secp256k1_ge_t p;
+    secp256k1_ge_set_gej(&p, &pj);
+    secp256k1_ecdsa_pubkey_serialize(&p, pubkey, pubkeylen, compressed);
+    return 1;
+}
+
+int secp256k1_ecdsa_pubkey_decompress(unsigned char *pubkey, int *pubkeylen) {
+    secp256k1_gej_t pj;
+    if (!secp256k1_ecdsa_pubkey_parse(&pj, pubkey, *pubkeylen))
+        return 0;
+    secp256k1_ge_t p;
+    secp256k1_ge_set_gej(&p, &pj);
+    secp256k1_ecdsa_pubkey_serialize(&p, pubkey, pubkeylen, 0);
+    return 1;
+}