Golang byte to hex

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Golang byte to hex

i have a hex representation and string version of this hex and I wanna compare them, if i will convert them both to byte and compare their bytes would it be correct??? and one more how to convert into fixed sized byte array for example [32]byte actually i have a []uint8 representation of the hash and string of this hash but unfortunately if i convert this string into byte and compare this bytes with []uint8 they are different absolutekly different but they both same hash First, byte is simply an alias for uint8. Just use one or the other. I'm not sure I understand your question, but the following example may have what you need: package main import "fmt" // A hexidecimal value ... // ... as a simple integer var x_int int = 0x1fe7d6df // ... as a string var x_string string = "1fe7d6df" // ... as an array of bytes var x_array [32]byte = [32]byte { '1', 'f', 'e', '7', 'd', '6', 'd', 'f', } // the string version will be converted to an array of bytes and stored here: var b_array [32]byte func main() { var i int // print the integer and string versions fmt.Printf("integer: %x", x_int) fmt.Printf("string: %s", x_string) // print the array version. Each byte is converted to a string fmt.Printf("array: ") for i = 0; x_array[i] != 0; i++ { fmt.Printf("%s", string(x_array[i])) } fmt.Printf(""); // compare the string version to the array version for i = 0; x_array[i] != 0; i++ { if x_string[i] != x_array[i] { fmt.Printf("The string and array differ at position %d",i+1) } } if x_array[i] == 0 { fmt.Printf("The string and array are the same") } // convert the string version into an array of bytes for i = 0; i < len(x_string); i++ { b_array[i] = x_string[i] } // convert it back into another string and print the string s := string(b_array[:len(x_string)]) fmt.Printf("string: %s",s) // compare the two arrays for i = 0; x_array[i] != 0; i++ { if b_array[i] != x_array[i] { fmt.Printf("The arrays differ at position %d",i+1) } } if x_array[i] == 0 { fmt.Printf("The arrays are the same") } } The above code is at the Go Playground: 1 Like I think he wants to compare []byte{0xFF} against "FF". If this is true hex.DecodeString should be able to help you: 1 Like That looks reasonable. Akezhan, if neither of these answers work for you, please show us examples of the data types you are working with (how they are declared, and how you use them), and if you can, explain more clearly what you are trying to do. @Akezhan_Esbolatov Why are you flagging your own post as off-topic? This topic was automatically closed 90 days after the last reply. New replies are no longer allowed. Home Categories FAQ/Guidelines Terms of Service Privacy Policy SHA1 hashes are frequently used to compute short identities for binary or text blobs. For example, the git revision control system uses SHA1s extensively to identify versioned files and directories. Here's how to compute SHA1 hashes in Go. func TestDataVersioningAvoidsUnnecessaryTruncation(t *testing.T) { t.Parallel() in := mustEncodeTestMessage(t, "VerTwoDataTwoPtr", "(val = 9, duo = 8, ptr1 = (val = 77), ptr2 = (val = 55))", []byte{ 0, 0, 0, 0, 7, 0, 0, 0, 0, 0, 0, 0, 2, 0, 2, 0, 9, 0, 0, 0, 0, 0, 0, 0, 8, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 1, 0, 0, 0, 4, 0, 0, 0, 1, 0, 0, 0, 77, 0, 0, 0, 0, 0, 0, 0, 55, 0, 0, 0, 0, 0, 0, 0, }) want := mustEncodeTestMessage(t, "Wrap2x2", "(mightNotBeReallyEmpty = (val = 9, duo = 8, ptr1 = (val = 77), ptr2 = (val = 55)))", []byte{ 0, 0, 0, 0, 8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 2, 0, 2, 0, 9, 0, 0, 0, 0, 0, 0, 0, 8, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 1, 0, 0, 0, 4, 0, 0, 0, 1, 0, 0, 0, 77, 0, 0, 0, 0, 0, 0, 0, 55, 0, 0, 0, 0, 0, 0, 0, }) msg, err := capnp.Unmarshal(in) if err != nil { t.Fatal("Unmarshal:", err) } // Read in the message as if it's an old client (less fields in schema). oldRoot, err := air.ReadRootVerEmpty(msg) if err != nil { t.Fatal("ReadRootVerEmpty:", err) } // Store the larger message into another segment. freshMsg, freshSeg, err := capnp.NewMessage(capnp.SingleSegment(nil)) if err != nil { t.Fatal("NewMessage:", err) } wrapEmpty, err := air.NewRootWrapEmpty(freshSeg) if err != nil { t.Fatal("NewRootWrapEmpty:", err) } if err := wrapEmpty.SetMightNotBeReallyEmpty(oldRoot); err != nil { t.Fatal("SetMightNotBeReallyEmpty:", err) } // Verify that it matches the expected serialization. out, err := freshMsg.Marshal() if err != nil { t.Fatal("Marshal:", err) } if !bytes.Equal(out, want) { t.Errorf("After copy, data is:%swant:%s", hex.Dump(out), hex.Dump(want)) } } Overview Package hex implements hexadecimal encoding and decoding. ErrLength reports an attempt to decode an odd-length input using Decode or DecodeString. The stream-based Decoder returns io.ErrUnexpectedEOF instead of ErrLength. var ErrLength = errors.New("encoding/hex: odd length hex string") func Decode ? func Decode(dst, src []byte) (int, error) Decode decodes src into DecodedLen(len(src)) bytes, returning the actual number of bytes written to dst. Decode expects that src contains only hexadecimal characters and that src has even length. If the input is malformed, Decode returns the number of bytes decoded before the error. Example package main import ( "encoding/hex" "fmt" "log" ) func main() { src := []byte("48656c6c6f20476f7068657221") dst := make([]byte, hex.DecodedLen(len(src))) n, err := hex.Decode(dst, src) if err != nil { log.Fatal(err) } fmt.Printf("%s", dst[:n]) } func DecodeString ? func DecodeString(s string) ([]byte, error) DecodeString returns the bytes represented by the hexadecimal string s. DecodeString expects that src contains only hexadecimal characters and that src has even length. If the input is malformed, DecodeString returns the bytes decoded before the error. Example package main import ( "encoding/hex" "fmt" "log" ) func main() { const s = "48656c6c6f20476f7068657221" decoded, err := hex.DecodeString(s) if err != nil { log.Fatal(err) } fmt.Printf("%s", decoded) } func DecodedLen ? func DecodedLen(x int) int DecodedLen returns the length of a decoding of x source bytes. Specifically, it returns x / 2. func Dump ? func Dump(data []byte) string Dump returns a string that contains a hex dump of the given data. The format of the hex dump matches the output of `hexdump -C` on the command line. Example package main import ( "encoding/hex" "fmt" ) func main() { content := []byte("Go is an open source programming language.") fmt.Printf("%s", hex.Dump(content)) } 00000000 47 6f 20 69 73 20 61 6e 20 6f 70 65 6e 20 73 6f |Go is an open so| 00000010 75 72 63 65 20 70 72 6f 67 72 61 6d 6d 69 6e 67 |urce programming| 00000020 20 6c 61 6e 67 75 61 67 65 2e | language.| func Dumper ? func Dumper(w io.Writer) io.WriteCloser Dumper returns a WriteCloser that writes a hex dump of all written data to w. The format of the dump matches the output of `hexdump -C` on the command line. Example package main import ( "encoding/hex" "os" ) func main() { lines := []string{ "Go is an open source programming language.", "", "We encourage all Go users to subscribe to golangannounce.", } stdoutDumper := hex.Dumper(os.Stdout) defer stdoutDumper.Close() for _, line := range lines { stdoutDumper.Write([]byte(line)) } } 00000000 47 6f 20 69 73 20 61 6e 20 6f 70 65 6e 20 73 6f |Go is an open so| 00000010 75 72 63 65 20 70 72 6f 67 72 61 6d 6d 69 6e 67 |urce programming| 00000020 20 6c 61 6e 67 75 61 67 65 2e 0a 57 65 20 65 6e | language..We en| 00000030 63 6f 75 72 61 67 65 20 61 6c 6c 20 47 6f 20 75 |courage all Go u| 00000040 73 65 72 73 20 74 6f 20 73 75 62 73 63 72 69 62 |sers to subscrib| 00000050 65 20 74 6f 20 67 6f 6c 61 6e 67 2d 61 6e 6e 6f |e to golang-anno| 00000060 75 6e 63 65 2e |unce.| func Encode ? func Encode(dst, src []byte) int Encode encodes src into EncodedLen(len(src)) bytes of dst. As a convenience, it returns the number of bytes written to dst, but this value is always EncodedLen(len(src)). Encode implements hexadecimal encoding. Example package main import ( "encoding/hex" "fmt" ) func main() { src := []byte("Hello Gopher!") dst := make([]byte, hex.EncodedLen(len(src))) hex.Encode(dst, src) fmt.Printf("%s", dst) } 48656c6c6f20476f7068657221 func EncodeToString ? func EncodeToString(src []byte) string EncodeToString returns the hexadecimal encoding of src. Example package main import ( "encoding/hex" "fmt" ) func main() { src := []byte("Hello") encodedStr := hex.EncodeToString(src) fmt.Printf("%s", encodedStr) } func EncodedLen ? func EncodedLen(n int) int EncodedLen returns the length of an encoding of n source bytes. Specifically, it returns n * 2. func NewDecoder ? 1.10 func NewDecoder(r io.Reader) io.Reader NewDecoder returns an io.Reader that decodes hexadecimal characters from r. NewDecoder expects that r contain only an even number of hexadecimal characters. func NewEncoder ? 1.10 func NewEncoder(w io.Writer) io.Writer NewEncoder returns an io.Writer that writes lowercase hexadecimal characters to w. type InvalidByteError ? InvalidByteError values describe errors resulting from an invalid byte in a hex string. type InvalidByteError byte func (InvalidByteError) Error ? func (e InvalidByteError) Error() string I've recently started a new job as a security engineer, and in preparation I've been going through the Cryptopals Crytpo challenges. In the first challenge, we are given a hex encoded string:which we need to decode, and then encode to base64, which should look like this:We can see what we're starting with and what we're supposed to end with, but how do we get there?What the Hex!?The first part of our problem is ecoding our input string that's been hex encoded, so what does it mean for a string to be hex encoded? To hex encode a string, we break each byte of the string into two 4-bit chunks(also called nibbles) and then we convert each of those chunks into their hexadecimal representation. That sounds really complicated, so let's break it down.First, if you're not familiar with binary and hexadecimal, do a quick read up here.A string is really just a collection of bytes. In Go, we can take a look at these bytes pretty easily:This will print out our byte values (in base10) for the string Hello, playgroundFrom our example above, we can see that H maps to 72. If we were to write 72 in binary, it would look like this:We are almost there! Now, we are going to split that byte into two halves. Each half is composed of 4 bits, giving us 0100 and 1000 .We now are going to represent each of those 4 bit chunks with their hexadecimal value. Here's a brief guide on converting binary to hex.0100 in hexadecimal is represented as 41000 in hexadecimal is represented as 8So if we were to Hex Encode H it would be 48Aren't we supposed to be decoding Hex?Let's take a look at the string we're given in the challenge again:Let's see if we can reverse engineer what we just did so we can decode the first character of our string. Remember, 2 hex characters decode to 1 byte, so the first byte of our decoded string will be represented by 4 and 9 from input.4 in binary is 01009 in binary is 1001So our first byte is 01001001In decimal that is 73, which in ASCII maps to I .We did it! We decoded our first character!This is going to take forever!Now that we know what's going on under the hood, let's see if we can't leverage some Go code to do this for us. Lucky for us, Go has some really handy built in functions around hex encoding. Here is what I came up with:The code is pretty straight forward, so I'm not going to dive too deep into it. All we are doing is making an empty byte slice and using Go's hex.Decode function to decode our input string to our newly created slice. After running the program, you should see this:That's not even it's final form!Now we have finished decoding our message, we have Base64 encode it. You can read up on Base64 Encoding a little more in depth here, but I'll give the quick rundown.To base64 encode a string, we're going to break it down into bytes again. We group three bytes together (giving us 24 bits), then split that into four 6-bit chunks. Then we'll cross reference each of the 6-bit chunks with this encoding table:Let's take a look at the first three characters of the string we're encoding: I'mI'm is represented by the bytes 73 39 109, which in binary is:To Base64 encode this, we will put all those bits together, and divide them into four 6-bit groups. What we'll end up with is this:Hey, that looks like it matches up with our desired output string, so we must be doing something right!There's a couple more things to keep in mind when base64 encoding. If you get to the end of your string, and the bits don't divide nicely by 6, add 0's until you fill your last 6-bit chunk. For example, if instead of encoding I'm, we were encoding just the string I', then it would look like this:So our encoded string would be SSc=You might be wondering where the = came from. When base64 encoding, you always have to end up with sections of 4 bytes. If you don't, you have to add padding at the end of your encoded string, and the padding character is =.Just get to the code already!Once again, Go has pretty nice built in functions for most of this, so our actual code is going to be very straightforward.We're going to add this function to our original code:Now all that's left to do is update our main function to call this after our hex decoding function, and we should see our final string.And there we have it, we've solved the first problem of Set 1 of Cryptopals. Feel free to play with this on Go Playground here.If you want to check out my solution on Github, where the code is a little cleaner, there are tests to run, a CLI to play with, and you can peek ahead to future problems I've solved, check it out here: Sometimes you need to encode bytes into a text.Most popular encodings are hex, where each byte is represented by 2 characters and base64 where each 3 bytes are encoded as 4 characters.Hex encode and decodeWe can encode a []byte into a string and decode from string into []byte. d := []byte{0x01, 0xff, 0x3a, 0xcd} s := hex.EncodeToString(d) fmt.Printf("Hex: %s", s) d2, err := hex.DecodeString(s) if err != nil { log.Fatalf("hex.DecodeString() failed with '%s'", err) } if !bytes.Equal(d, d2) { log.Fatalf("decoded version is different than original") } Hex encoding with fmt.SprintfWe can encode to string using fmt.Sprintf and %x directive. Similarly, we can decode using fmt.Sscanf and %x.Directive %x supports integers in addtion to []byte. d := []byte{0x01, 0xff, 0x3a, 0xcd} s := fmt.Sprintf("%x", d) fmt.Printf("Hex: %s", s) var decoded []byte _, err := fmt.Sscanf(s, "%x", &decoded) if err != nil { log.Fatalf("fmt.Sscanf() failed with '%s'", err) } if !bytes.Equal(d, decoded) { log.Fatalf("decoded version is different than original") } n := 3824 fmt.Printf("%d in hex is 0x%x", n, n) Hex: 01ff3acd 3824 in hex is 0xef0 Hex encoding to writer, decoding from readerFor encoding and decoding larger values in streaming mode, we can encode to a io.Writer and decode from io.Reader. d := []byte{0x01, 0xff, 0x3a, 0xcd} writer := &bytes.Buffer{} hexWriter := hex.NewEncoder(writer) _, err := hexWriter.Write(d) if err != nil { log.Fatalf("hexWriter.Write() failed with '%s'", err) } encoded := writer.Bytes() fmt.Printf("Hex: %s", string(encoded)) reader := bytes.NewBuffer(encoded) hexReader := hex.NewDecoder(reader) decoded, err := ioutil.ReadAll(hexReader) if err != nil { fmt.Printf("ioutil.ReadAll() failed with '%s'", err) } if !bytes.Equal(d, decoded) { log.Fatalf("decoded version is different than original") } Base64 encode and decodeWe can encode a []byte into a string and decode from string into []byte. d := []byte{0x01, 0xff, 0x3a, 0xcd} s := base64.StdEncoding.EncodeToString(d) fmt.Printf("base64: %s", s) d2, err := base64.StdEncoding.DecodeString(s) if err != nil { log.Fatalf("hex.DecodeString() failed with '%s'", err) } if !bytes.Equal(d, d2) { log.Fatalf("decoded version is different than original") } URL-safe base64Original base64 encoding unfortunately might produce characters that are not valid in urls.Given that urls are important those days we have a variant of base64 encoding that doesn't have that flaw: d := []byte{0x01, 0xff, 0x3a, 0xcd} s := base64.URLEncoding.EncodeToString(d) fmt.Printf("base64: %s", s) d2, err := base64.URLEncoding.DecodeString(s) if err != nil { log.Fatalf("hex.DecodeString() failed with '%s'", err) } if !bytes.Equal(d, d2) { log.Fatalf("decoded version is different than original") } Base64 encoding to writer, decoding from readerFor encoding and decoding larger values in streaming mode, we can encode to an io.Writer and decode from io.Reader. d := []byte{0x01, 0xff, 0x3a, 0xcd} writer := &bytes.Buffer{} base64Writer := base64.NewEncoder(base64.StdEncoding, writer) _, err := base64Writer.Write(d) if err != nil { log.Fatalf("base64Writer.Write() failed with '%s'", err) } err = base64Writer.Close() if err != nil { log.Fatalf("base64Writer.Close() failed with '%s'", err) } encoded := writer.Bytes() fmt.Printf("Base64: %s", string(encoded)) reader := bytes.NewBuffer(encoded) base64Reader := base64.NewDecoder(base64.StdEncoding, reader) decoded, err := ioutil.ReadAll(base64Reader) if err != nil { fmt.Printf("ioutil.ReadAll() failed with '%s'", err) } if !bytes.Equal(d, decoded) { log.Fatalf("decoded version is different than original") }

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