diff --git a/implementation-profiles/profile.md b/implementation-profiles/profile.md
new file mode 100644
index 0000000..3bd94ad
--- /dev/null
+++ b/implementation-profiles/profile.md
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+# DP3-T Implementation profile 
+Against version 2020/4/8 of the whitepaper
+
+## Design 2
+
+### General
+
+Byte sequences are 8 bit octed strings.
+
+### Generating Empheral IDs
+
+The H is an SHA256 as per per RFC 6234
+
+TRUNKCATE128() takes the first 32 bytes (of the 64 byte SHA256)
+
+Test vector:
+ 
+    Seed:     0000000000000000000000000000000000000000000000000000000000000000 
+    			(i.e. 0x00, 0x00 .. 0x00 32 bytes)
+    H (seed): 66687aadf862bd776c8fc18b8e9f8e20089714856ee233b3902a591d0d5f2925
+    TRUNKCATE128(H(seed)): 
+              66687aadf862bd776c8fc18b8e9f8e20
+
+### Local storare / handling of ‘t’
+
+‘t’ is a network order (big endian) unsigned 32 bit number. I.e. the number 1 is encoded transmitted as 0x00, 0x00, 0x00, 0x01 on the wire.
+
+‘t’ contains the unix UTC/Z timestamp as defined by RFC 3339.
+
+So the H(EphID||t) stored is a SHA256 taken over 16 + 4 = 20 sequentiel bytes in that order (EphID, then time).
+
+Test vector:
+
+	Time: 2020-4-10 00:00:00 UTC
+	T = 1586476800 
+	        5E8FB700 (4 bytes)
+	EphID || t = 
+	        66687aadf862bd776c8fc18b8e9f8e201586476800) (16+4 butes)
+	H(EphID || t)
+	        109708e29597623f56fd365ba92f1c717ca23994aabd7939822909c465cb10a5 (32 bytes)
+
+### Cuckoo filter and serialisation
+
+The depth of the Cuckoo filter shall be 4.
+
+The Cuckoo filter shall be serialised as:
+
+-	Depth:			unsigned 32 bit integer (A)
+-   	Number of slots: 	unsigned 32 bit integer (S)
+- 	Number of buckets:	unsigned 32 bit integer (B)
+-	Buckets B x ( A x slotsID)
+-		with the slotID an unsigned 32 bit integer. 
+-	Slots(numbered 0 .. slotsID) 	S x ( key )
+-		with the key a 31 bit  unsigned int;
+-		the topbit denotes a populated (0) or empty (1) slot.
+
+### Cuckoo filter publication
+
+The filter should be published prefixed by an RFC3161 timestamp. 
+
+
+
+
+## Design 1
+
+The PRF used is HMAC-SHA256 as per RFC 6234 and RFC 2104 - and and where Skt_ is used as the `key’ and the string  “broadcast key” (without trailing \0, i.e. exactly those 13 US-ASCII characters is the plaintext.
+
+The PRG used is AES128 in counter mode; with the IV set to a 128 bit unsigned number in network order (i.e the first IV is a byte array if [  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01 ]) we start at 0, not 1
+
+and the plaintext 128 bits of 0’s.
+
+
+
diff --git a/implementation-profiles/vectors.c b/implementation-profiles/vectors.c
new file mode 100644
index 0000000..bb34191
--- /dev/null
+++ b/implementation-profiles/vectors.c
@@ -0,0 +1,66 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <strings.h>
+
+#include <openssl/sha.h>
+#include <openssl/err.h>
+#include <openssl/rand.h>
+#include <openssl/hmac.h>
+#include <openssl/aes.h>
+#include <openssl/evp.h>
+#include <openssl/crypto.h>
+
+#include <strings.h>
+#include <stdlib.h>
+#include <time.h>
+
+
+void printhex(uint8_t * hashed_seed, size_t len) {
+   for(int i = 0; i < len; i++) 
+      printf("%02x",hashed_seed[i]);
+   printf(" (size %lu)\n", len);
+};
+
+int main(int argc, char ** argv) {
+  SHA256_CTX sha256;
+
+  uint8_t seed[ 32 ];
+  bzero(seed,sizeof(seed));
+
+  printf("Seed:\t\t"); printhex(seed,sizeof(seed));
+
+  uint8_t hashed_seed[32];
+  SHA256_Init(&sha256);
+  SHA256_Update(&sha256, seed, 32);
+  SHA256_Final(hashed_seed,  &sha256);
+  printf("H(Seed):\t\t"); printhex(hashed_seed, 32);
+
+  printf("TRUNCATE128(H(Seed)):\t"); printhex(hashed_seed, 128 / 8 );
+
+  struct tm ts = { 
+	.tm_sec = 0, .tm_min = 0, .tm_hour = 0, 
+	.tm_mon = 3, .tm_year = 120, 
+	.tm_wday = 5, 
+	.tm_isdst = 0, .tm_gmtoff = 0
+  };
+
+  time_t t = timegm(&ts);
+  printf("Time:\t\t%lu\n", t);
+  uint8_t tbuff[4];
+  *(uint32_t *)tbuff= htonl(t);
+
+  printf("t:\t\t"); printhex(tbuff,4);
+
+  uint8_t ephid_concat_t[16 + 4];
+  bcopy(hashed_seed, ephid_concat_t +  0, 16);
+  bcopy(tbuff       ,ephid_concat_t + 16, 4);
+
+  printf("ephid||t:\t\t"); printhex(ephid_concat_t, 16+4);
+
+  uint8_t hash[32];
+  SHA256_Init(&sha256);
+  SHA256_Update(&sha256, ephid_concat_t, 16 + 4);
+  SHA256_Final(hash,  &sha256);
+  printf("H(E || t)):\t"); printhex(hash, 32);
+
+}