fix(textual): Use HEX instead of base64 (#12954)

## Description

ref: https://github.com/cosmos/cosmos-sdk/pull/12910#discussion_r943984849



---

### Author Checklist

*All items are required. Please add a note to the item if the item is not applicable and
please add links to any relevant follow up issues.*

I have...

- [ ] included the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] added `!` to the type prefix if API or client breaking change
- [ ] targeted the correct branch (see [PR Targeting](https://github.com/cosmos/cosmos-sdk/blob/main/CONTRIBUTING.md#pr-targeting))
- [ ] provided a link to the relevant issue or specification
- [ ] followed the guidelines for [building modules](https://github.com/cosmos/cosmos-sdk/blob/main/docs/building-modules)
- [ ] included the necessary unit and integration [tests](https://github.com/cosmos/cosmos-sdk/blob/main/CONTRIBUTING.md#testing)
- [ ] added a changelog entry to `CHANGELOG.md`
- [ ] included comments for [documenting Go code](https://blog.golang.org/godoc)
- [ ] updated the relevant documentation or specification
- [ ] reviewed "Files changed" and left comments if necessary
- [ ] confirmed all CI checks have passed

### Reviewers Checklist

*All items are required. Please add a note if the item is not applicable and please add
your handle next to the items reviewed if you only reviewed selected items.*

I have...

- [ ] confirmed the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] confirmed `!` in the type prefix if API or client breaking change
- [ ] confirmed all author checklist items have been addressed 
- [ ] reviewed state machine logic
- [ ] reviewed API design and naming
- [ ] reviewed documentation is accurate
- [ ] reviewed tests and test coverage
- [ ] manually tested (if applicable)

docs/architecture/adr-050-sign-mode-textual-annex1.md

@@ -214,7 +214,7 @@ Rendered as either ISO8601 (`2021-01-01T12:00:00Z`).
 
 ### bytes
 
-- Bytes are rendered in base64.
+- Bytes are rendered in hexadecimal, all capital letters, without the `0x` prefix.
 
 ### address bytes
 

docs/architecture/adr-050-sign-mode-textual.md

@@ -93,7 +93,7 @@ We define "transaction envelope" as all data in a transaction that is not in the
 ```
 Chain ID: <string>
 Account number: <uint64>
-*Public Key: <base64_string>
+*Public Key: <hex_string>
 Sequence: <uint64>
 <TxBody>                                                    // See #8.
 Fee: <coins>                                                // See value renderers for coins encoding.
@@ -112,7 +112,7 @@ Tip: <string>
 *<repeated Any>
 *This transaction has <int> other signers:                  // Skipped if there is only one signer
 *Signer (<int>/<int>):
-*Public Key: <base64_string>
+*Public Key: <hex_string>
 *Sequence: <uint64>
 *End of other signers
 ```
@@ -222,7 +222,7 @@ SIGN_MODE_TEXTUAL:
 ```
 Chain ID: simapp-1
 Account number: 10
-*Public Key: iQ...==        // Base64 pubkey
+*Public Key: iQ...==        // Hex pubkey
 Sequence: 2
 This transaction has 1 message:
 Message (1/1): bank v1beta1 send coins
@@ -481,7 +481,7 @@ SIGN_MODE_TEXTUAL is purely additive, and doesn't break any backwards compatibil
 
 ### Negative
 
-- Some fields are still encoded in non-human-readable ways, such as public keys in base64.
+- Some fields are still encoded in non-human-readable ways, such as public keys in hexadecimal.
 - New ledger app needs to be released, still unclear
 
 ### Neutral

tx/textual/valuerenderer/bytes.go

@@ -2,8 +2,9 @@ package valuerenderer
 
 import (
 	"context"
-	"encoding/base64"
+	"encoding/hex"
 	"io"
+	"strings"
 
 	"google.golang.org/protobuf/reflect/protoreflect"
 )
@@ -14,7 +15,7 @@ type bytesValueRenderer struct{}
 var _ ValueRenderer = bytesValueRenderer{}
 
 func (vr bytesValueRenderer) Format(ctx context.Context, v protoreflect.Value, w io.Writer) error {
-	_, err := io.WriteString(w, base64.StdEncoding.EncodeToString(v.Bytes()))
+	_, err := io.WriteString(w, strings.ToUpper(hex.EncodeToString(v.Bytes())))
 	return err
 }
 
@@ -24,7 +25,7 @@ func (vr bytesValueRenderer) Parse(_ context.Context, r io.Reader) (protoreflect
 		return protoreflect.ValueOfBytes([]byte{}), err
 	}
 
-	data, err := base64.StdEncoding.DecodeString(string(formatted))
+	data, err := hex.DecodeString(string(formatted))
 	if err != nil {
 		return protoreflect.ValueOfBytes([]byte{}), err
 	}

tx/textual/valuerenderer/bytes_test.go

@@ -2,7 +2,7 @@ package valuerenderer_test
 
 import (
 	"context"
-	"encoding/hex"
+	"encoding/base64"
 	"encoding/json"
 	"os"
 	"strings"
@@ -12,8 +12,10 @@ import (
 	"google.golang.org/protobuf/reflect/protoreflect"
 )
 
-func TestFormatBytes(t *testing.T) {
+func TestBytesJsonTestCases(t *testing.T) {
 	var testcases []bytesTest
+	// Bytes.json contains bytes that are represented in base64 format, and
+	// their expected results in hex.
 	raw, err := os.ReadFile("../internal/testdata/bytes.json")
 	require.NoError(t, err)
 
@@ -21,25 +23,31 @@ func TestFormatBytes(t *testing.T) {
 	require.NoError(t, err)
 
 	for _, tc := range testcases {
-		data, err := hex.DecodeString(tc.hex)
+		data, err := base64.StdEncoding.DecodeString(tc.base64)
 		require.NoError(t, err)
 
-		r, err := valueRendererOf(data)
+		valrend, err := valueRendererOf(data)
 		require.NoError(t, err)
 
 		b := new(strings.Builder)
-		err = r.Format(context.Background(), protoreflect.ValueOfBytes(data), b)
+		err = valrend.Format(context.Background(), protoreflect.ValueOfBytes(data), b)
 		require.NoError(t, err)
-		require.Equal(t, tc.expRes, b.String())
+		require.Equal(t, tc.hex, b.String())
+
+		// Round trip
+		r := strings.NewReader(tc.hex)
+		val, err := valrend.Parse(context.Background(), r)
+		require.NoError(t, err)
+		require.Equal(t, tc.base64, base64.StdEncoding.EncodeToString(val.Bytes()))
 	}
 }
 
 type bytesTest struct {
 	hex    string
-	expRes string
+	base64 string
 }
 
 func (t *bytesTest) UnmarshalJSON(b []byte) error {
-	a := []interface{}{&t.hex, &t.expRes}
+	a := []interface{}{&t.hex, &t.base64}
 	return json.Unmarshal(b, &a)
 }