chore: Audit crypto folder (#11932)

## Description

ref: #11362 

I did **NOT** review the following folders, as they contain cryptography which I don't think I'm competent enough to give a useful review:
- [ ] `crypto/xsalsa20symmetric` (new in v046, ported from TM i think)
- [ ] `crypto/keys/secp256k1` (some new stuff in v046 too)

Also performed some manual tests as part of #11939:

  - [x] Create keys on v0.45, make sure they still work in v0.46 #11939 (comment)
  - [x] Create new keys in v0.46 #11939 (comment)
  - [x] `--multisig` flag works with an address that's not in the keyring (see [repro](#9553))



---

### 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)

CHANGELOG.md

@@ -89,7 +89,8 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 ### API Breaking Changes
 
-* (types ) [#11881](https://github.com/cosmos/cosmos-sdk/issues/11881) Rename `AccAddressFromHex` to `AccAddressFromHexUnsafe`.
+* (crypto/keyring) [#11932](https://github.com/cosmos/cosmos-sdk/pull/11932) Remove `Unsafe*` interfaces from keyring package. Please use interface casting if you wish to access those unsafe functions.
+* (types) [#11881](https://github.com/cosmos/cosmos-sdk/issues/11881) Rename `AccAddressFromHex` to `AccAddressFromHexUnsafe`.
 * (types) [#11788](https://github.com/cosmos/cosmos-sdk/pull/11788) The `Int` and `Uint` types have been moved to their own dedicated module, `math`. Aliases are kept in the SDK's root `types` package, however, it is encouraged to utilize the new `math` module. As a result, the `Int#ToDec` API has been removed.
 * (grpc) [\#11642](https://github.com/cosmos/cosmos-sdk/pull/11642) The `RegisterTendermintService` method in the `tmservice` package now requires a `abciQueryFn` query function parameter.
 * [\#11496](https://github.com/cosmos/cosmos-sdk/pull/11496) Refactor abstractions for snapshot and pruning; snapshot intervals eventually pruned; unit tests.
@@ -98,7 +99,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * [\#10950](https://github.com/cosmos/cosmos-sdk/pull/10950) Add `envPrefix` parameter to `cmd.Execute`.
 * (x/mint) [\#10441](https://github.com/cosmos/cosmos-sdk/pull/10441) The `NewAppModule` function now accepts an inflation calculation function as an argument.
 * [\#10295](https://github.com/cosmos/cosmos-sdk/pull/10295) Remove store type aliases from /types
-* [\#9695](https://github.com/cosmos/cosmos-sdk/pull/9695) Migrate keys from `Info` -> `Record`
+* [\#9695](https://github.com/cosmos/cosmos-sdk/pull/9695) Migrate keys from `Info` (serialized as amino) -> `Record` (serialized as proto)
     * Add new `codec.Codec` argument in:
         * `keyring.NewInMemory`
         * `keyring.New`

client/keys/export.go

@@ -2,13 +2,15 @@ package keys
 
 import (
 	"bufio"
+	"encoding/hex"
 	"fmt"
 
 	"github.com/spf13/cobra"
 
 	"github.com/cosmos/cosmos-sdk/client"
 	"github.com/cosmos/cosmos-sdk/client/input"
 	"github.com/cosmos/cosmos-sdk/crypto/keyring"
+	"github.com/cosmos/cosmos-sdk/crypto/types"
 )
 
 const (
@@ -75,7 +77,7 @@ func exportUnsafeUnarmored(cmd *cobra.Command, uid string, buf *bufio.Reader, kr
 		return nil
 	}
 
-	hexPrivKey, err := keyring.NewUnsafe(kr).UnsafeExportPrivKeyHex(uid)
+	hexPrivKey, err := unsafeExportPrivKeyHex(kr.(unsafeExporter), uid)
 	if err != nil {
 		return err
 	}
@@ -84,3 +86,20 @@ func exportUnsafeUnarmored(cmd *cobra.Command, uid string, buf *bufio.Reader, kr
 
 	return nil
 }
+
+// unsafeExporter is implemented by key stores that support unsafe export
+// of private keys' material.
+type unsafeExporter interface {
+	// ExportPrivateKeyObject returns a private key in unarmored format.
+	ExportPrivateKeyObject(uid string) (types.PrivKey, error)
+}
+
+// unsafeExportPrivKeyHex exports private keys in unarmored hexadecimal format.
+func unsafeExportPrivKeyHex(ks unsafeExporter, uid string) (privkey string, err error) {
+	priv, err := ks.ExportPrivateKeyObject(uid)
+	if err != nil {
+		return "", err
+	}
+
+	return hex.EncodeToString(priv.Bytes()), nil
+}

client/keys/migrate.go

@@ -34,10 +34,10 @@ func runMigrateCmd(cmd *cobra.Command, _ []string) error {
 		return err
 	}
 
-	if _, err = clientCtx.Keyring.MigrateAll(); err != nil {
+	if err = clientCtx.Keyring.MigrateAll(); err != nil {
 		return err
 	}
 
-	cmd.Println("Keys migration has been successfully executed")
+	cmd.Println("Keys migration has been successfully executed.")
 	return nil
 }

client/keys/migrate_test.go

@@ -55,9 +55,9 @@ func (s *MigrateTestSuite) Test_runListAndShowCmd() {
 	serializedLegacyMultiInfo := keyring.MarshalInfo(legacyMultiInfo)
 
 	item := design99keyring.Item{
-		Key:         s.appName,
+		Key:         s.appName + ".info",
 		Data:        serializedLegacyMultiInfo,
-		Description: "SDK kerying version",
+		Description: "SDK keyring version",
 	}
 
 	//run test simd keys list - to see that the migrated key is there

crypto/keyring/doc.go

@@ -1,17 +1,11 @@
 // Package keys provides common key management API.
 //
 //
-// The Keybase interface
+// The Keyring interface
 //
-// The Keybase interface defines the methods that a type needs to implement to be used
+// The Keyring interface defines the methods that a type needs to implement to be used
 // as key storage backend. This package provides few implementations out-of-the-box.
 //
-// NewLegacy
-//
-// The NewLegacy constructor returns an on-disk implementation backed by LevelDB storage that has been
-// the default implementation used by the SDK until v0.38.0. Due to security concerns, it is
-// recommended to drop it in favor of the NewKeyring constructor as it will be removed in future releases.
-//
 // NewInMemory
 //
 // The NewInMemory constructor returns an implementation backed by an in-memory, goroutine-safe