diff --git a/quic.c b/quic.c
new file mode 100644
index 0000000..a2dc291
--- /dev/null
+++ b/quic.c
@@ -0,0 +1,137 @@
+#include "quic.h"
+
+static const uint32_t supported_versions[] = {
+	1,		// version 1, RFC 9000
+	0x6b3343cf,	// version 2, RFC 9369
+};
+
+/**
+ * Packet number.
+ */
+struct quic_pnumber {
+	uint8_t d1;
+	uint8_t d2;
+	uint8_t d3;
+	uint8_t d4;
+};
+
+uint64_t quic_parse_varlength(uint8_t *variable, uint64_t *mlen) {
+	if (mlen && *mlen == 0) return 0;
+	uint64_t vr = (*variable & 0x3F);
+	uint8_t len = 1 << (*variable >> 6);
+
+	if (mlen) {
+		if (*mlen < len) return 0;
+		*mlen = len;
+	}
+
+	++variable;
+	for (uint8_t i = 1; i < len; i++) {
+		vr = (vr << 8) + *variable;
+		++variable;
+	}
+
+	return vr;
+}
+
+int quic_parse_data(uint8_t *raw_payload, uint32_t raw_payload_len,
+		struct quic_lhdr **qch, uint32_t *qch_len,
+		struct quic_cids *qci,
+		uint8_t **payload, uint32_t *plen) {
+	if (	raw_payload == NULL || 
+		raw_payload_len < sizeof(struct quic_lhdr)) 
+		goto invalid_packet;
+
+	struct quic_lhdr *nqch = (struct quic_lhdr *)raw_payload;
+	uint32_t left_len = raw_payload_len - sizeof(struct quic_lhdr);
+	uint8_t *cur_rawptr = raw_payload + sizeof(struct quic_lhdr);
+	if (!nqch->fixed)
+		return -EPROTO;
+
+	uint8_t found = 0;
+	for (uint8_t i = 0; i < sizeof(supported_versions); i++) {
+		if (nqch->version == supported_versions[i]) {
+			found = 1;
+		}
+	}
+
+	if (!found) 
+		return -EPROTO;
+
+	if (left_len < 2) goto invalid_packet;
+	struct quic_cids nqci = {0};
+
+	nqci.dst_len = *cur_rawptr++;
+	left_len--;
+	if (left_len < nqci.dst_len) goto invalid_packet;
+	nqci.dst_id = cur_rawptr;
+	cur_rawptr += nqci.dst_len;
+	left_len -= nqci.dst_len;
+
+	nqci.src_len = *cur_rawptr++;
+	left_len--;
+	if (left_len < nqci.src_len) goto invalid_packet;
+	nqci.src_id = cur_rawptr;
+	cur_rawptr += nqci.src_len;
+	left_len -= nqci.src_len;
+
+	if (qch) *qch = nqch;
+	if (qch_len) {
+		*qch_len = sizeof(struct quic_lhdr) + 
+			nqci.src_len + nqci.dst_len;
+	}
+	if (qci) *qci = nqci;
+	if (payload) *payload = cur_rawptr;
+	if (plen) *plen = left_len;
+
+	return 0;
+
+invalid_packet:
+	return -EINVAL;
+}
+
+int quic_parse_initial_message(uint8_t *inpayload, uint32_t inplen,
+			const struct quic_lhdr *qch, 
+			struct quici_hdr *qhdr,
+			uint8_t **payload, uint32_t *plen) {
+	if (inplen < 3) goto invalid_packet;
+	struct quici_hdr nqhdr;
+
+	uint8_t *cur_ptr = inpayload;
+	uint32_t left_len = inplen;
+	uint64_t tlen = left_len;
+
+	nqhdr.token_len = quic_parse_varlength(cur_ptr, &tlen);
+	nqhdr.token = cur_ptr + tlen;
+	
+	if (left_len < nqhdr.token_len + tlen) 
+		goto invalid_packet;
+	cur_ptr += tlen + nqhdr.token_len;
+	left_len -= tlen + nqhdr.token_len;
+
+	tlen = left_len;
+	nqhdr.length = quic_parse_varlength(cur_ptr, &tlen);
+
+	if (left_len != nqhdr.length + tlen && 
+		left_len <= qch->number_length + 1)
+		goto invalid_packet;
+
+	uint32_t packet_number = 0;
+
+	for (uint8_t i = 0; i <= qch->number_length; i++) {
+		packet_number = (packet_number << 8) + *cur_ptr++;
+		left_len--;
+	}
+
+	nqhdr.packet_number = packet_number;
+
+	if (qhdr) *qhdr = nqhdr;
+	if (payload) *payload = cur_ptr;
+	if (plen) *plen = left_len;
+
+	return 0;
+
+invalid_packet:
+	lgerror("QUIC invalid Initial packet", -EINVAL);
+	return -EINVAL;
+}
diff --git a/quic.h b/quic.h
new file mode 100644
index 0000000..cf46df6
--- /dev/null
+++ b/quic.h
@@ -0,0 +1,113 @@
+#ifndef QUIC_H
+#define QUIC_H
+#include "types.h"
+
+/**
+* @macro
+*
+* :macro:`NGTCP2_INITIAL_SALT_V1` is a salt value which is used to
+* derive initial secret.  It is used for QUIC v1.
+*/
+#define QUIC_INITIAL_SALT_V1 \
+ "\x38\x76\x2c\xf7\xf5\x59\x34\xb3\x4d\x17\x9a\xe6\xa4\xc8\x0c\xad" \
+ "\xcc\xbb\x7f\x0a"
+
+/**
+* @macro
+*
+* :macro:`NGTCP2_INITIAL_SALT_V2` is a salt value which is used to
+* derive initial secret.  It is used for QUIC v2.
+*/
+#define QUIC_INITIAL_SALT_V2 \
+ "\x0d\xed\xe3\xde\xf7\x00\xa6\xdb\x81\x93\x81\xbe\x6e\x26\x9d\xcb" \
+ "\xf9\xbd\x2e\xd9"
+
+#define QUIC_INITIAL_TYPE_V1 0x00
+#define QUIC_0_RTT_TYPE_V1 0x01
+#define QUIC_HANDSHAKE_TYPE_V1 0x02
+#define QUIC_RETRY_TYPE_V1 0x03
+
+#define QUIC_INITIAL_TYPE_V2 0b01
+#define QUIC_0_RTT_TYPE_V2 0b10
+#define QUIC_HANDSHAKE_TYPE_V2 0b11
+#define QUIC_RETRY_TYPE_V2 0b00
+
+/**
+ * Quic Large Header
+ */
+struct quic_lhdr {
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+	uint8_t number_length: 2;
+	uint8_t reserved: 2;
+	uint8_t type: 2;
+	uint8_t fixed: 1;
+	uint8_t form: 1;
+#elif __BYTE_ORDER == __BIG_ENDIAN
+	uint8_t form: 1;
+	uint8_t fixed: 1;
+	uint8_t type: 2;
+	uint8_t reserved: 2;
+	uint8_t number_length: 2;
+#else
+#error "Undefined endian"
+#endif
+
+	uint32_t version;
+};
+
+/**
+ * Quic Large Header Ids 
+ * (separated from the original header because of varying dst 
+ */
+struct quic_cids {
+	uint8_t dst_len;
+	uint8_t *dst_id;
+	uint8_t src_len;
+	uint8_t *src_id;
+};
+
+/**
+ * Parses QUIС raw data (UDP payload) to quic large header and 
+ * quic payload.
+ *
+ * \qch_len is sizeof(qch) + qci->dst_len + qci->src_id
+ * \payload is Type-Specific payload (#17.2).
+ */
+int quic_parse_data(uint8_t *raw_payload, uint32_t raw_payload_len,
+		struct quic_lhdr **qch, uint32_t *qch_len,
+		struct quic_cids *qci,
+		uint8_t **payload, uint32_t *plen);
+		
+
+/**
+ * Parses QUIC variable-length integer. (#16)
+ * \variable is a pointer to the sequence to be parsed
+ * (varlen integer in big endian format)
+ *
+ * \mlen Used to signal about variable length and validate left length
+ * in the buffer.
+ */
+uint64_t quic_parse_varlength(uint8_t *variable, uint64_t *mlen);
+
+// quici stands for QUIC Initial
+
+/**
+ * This structure should be parsed
+ */
+struct quici_hdr {
+	uint64_t token_len;
+	uint8_t *token;
+	uint64_t length;
+	uint32_t packet_number;
+};
+
+/**
+ * Parses QUIC initial payload.
+ * \inpayload is a raw QUIC payload (payload after quic large header)
+ */
+int quic_parse_initial_message(uint8_t *inpayload, uint32_t inplen,
+			const struct quic_lhdr *qch,
+			struct quici_hdr *qhdr,
+			uint8_t **payload, uint32_t *plen);
+
+#endif /* QUIC_H */