```

#### 3.2.2 Generate a private key with RSA

Use the following command to generate a private key with RSA:

```sh
openssl genrsa -out private.key 2048
```

A response similar to this one should be displayed:

```
Generating RSA private key, 2048 bit long modulus
............................................+++
...........+++

Valid values
```
ssh-ed25519
******@****.***
******@****.***
ecdsa-sha2-nistp256
ecdsa-sha2-nistp384
ecdsa-sha2-nistp521
rsa-sha2-256
rsa-sha2-512
ssh-rsa
ssh-dss
```

`--sftp=kex-algos=...` specifies the supported key-exchange algorithms in preference order.

Valid values: 

```
curve25519-sha256
******@****.***

Using `gotestjsonbuildtext=1` restores the 1.23 behavior.
This setting will be removed in a future release, Go 1.28 at the earliest.

Go 1.24 changed [`crypto/rsa`](/pkg/crypto/rsa) to require RSA keys to be at
least 1024 bits. This behavior can be controlled with the `rsa1024min` setting.
Using `rsa1024min=0` restores the Go 1.23 behavior.

pkg crypto/elliptic, func MarshalCompressed(Curve, *big.Int, *big.Int) []uint8
pkg crypto/elliptic, func UnmarshalCompressed(Curve, []uint8) (*big.Int, *big.Int)
pkg crypto/rsa, method (*PrivateKey) Equal(crypto.PrivateKey) bool
pkg crypto/rsa, method (*PublicKey) Equal(crypto.PublicKey) bool
pkg crypto/tls, method (*Dialer) Dial(string, string) (net.Conn, error)

		os.Remove(outputFileName)
	}
}

func generateKeys() {
	privatekey, err := rsa.GenerateKey(crand.Reader, 2048)
	if err != nil {
		fmt.Printf("error generating key: %s n", err)
		os.Exit(1)
	}

	// dump private key to file
	privateKeyBytes := x509.MarshalPKCS1PrivateKey(privatekey)
	privateKeyBlock := &pem.Block{
		Type:  "RSA PRIVATE KEY",
		Bytes: privateKeyBytes,
	}

// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package main

import (
	"crypto/rsa"
	"crypto/x509"
	"encoding/base64"
	"encoding/pem"
	"log"
)

func bytesToPrivateKey(priv []byte) (*rsa.PrivateKey, error) {
	// Try PEM
	if block, _ := pem.Decode(priv); block != nil {
		return x509.ParsePKCS1PrivateKey(block.Bytes)
	}
	// Try base 64

ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABgQDES4saDDRpoHDVmiYESEQrCYhw8EK7Utj/A/lqxiqZlP6Il3aN2fWu6uJQdWAovZxNeXUf8LIujisW1mJWGZPql0SLKVq6IZ707OAGmKA59IXfF5onRoU9+K4UDL7BJFfix6/3F5OV2WB3ChFrOrXhJ0CZ0sVAfGcV4q72kS19YjZNX3fqCc2HF8UQEaZGKIkw5MtdZI9a1P2bqnPuPGJybRFUzyoQXPge45QT5jnpcsAXOuXcGxbjuqaaHXFNTSKAkCU93TcjAbqUMkTz2mnFz/MnrKJTECN3Fy0GPCCQ5dxmG8p8DyMiNl7JYkX2r3XYgxmioCzkcg8fDs5p0CaQcipu+MA7iK7APKq7v4Zr/wNltXHI3DE9S8J88Hxb2FZAyEhCRfcgGmCVfoZxVNCRHNkGYzfe63BkxtnseUCzpYEhKv02H5u9rjFpdMY37kDfHDVqBbgut...

	publicKey := func(priv any) any {
		switch k := priv.(type) {
		case *rsa.PrivateKey:
			return &k.PublicKey
		case *ecdsa.PrivateKey:
			return &k.PublicKey
		default:
			return nil
		}
	}

	pemBlockForKey := func(priv any) *pem.Block {
		switch k := priv.(type) {
		case *rsa.PrivateKey:
			return &pem.Block{Type: "RSA PRIVATE KEY", Bytes: x509.MarshalPKCS1PrivateKey(k)}
		case *ecdsa.PrivateKey:

pkg crypto/elliptic, type Curve interface, ScalarBaseMult //deprecated #52221
pkg crypto/elliptic, type Curve interface, ScalarMult //deprecated #52221
pkg crypto/rsa, func GenerateMultiPrimeKey //deprecated #56921
pkg crypto/rsa, type PrecomputedValues struct, CRTValues //deprecated #56921
pkg crypto/tls, const QUICEncryptionLevelApplication = 3 #44886
pkg crypto/tls, const QUICEncryptionLevelApplication QUICEncryptionLevel #44886

pkg crypto/ecdsa, method (*PrivateKey) Sign(io.Reader, []uint8, crypto.SignerOpts) ([]uint8, error)
pkg crypto/rsa, method (*PSSOptions) HashFunc() crypto.Hash
pkg crypto/rsa, method (*PrivateKey) Public() crypto.PublicKey
pkg crypto/rsa, method (*PrivateKey) Sign(io.Reader, []uint8, crypto.SignerOpts) ([]uint8, error)
pkg crypto/rsa, type PSSOptions struct, Hash crypto.Hash