In a method of provisioning a virtual machine (VM) to a computing network (401), a VM manager or provisioner (403, 408) encrypts a virtual machine using a key bound to at least one security profile indicative of one or more security requirements that a computing resource (402) of the computing network (401) must satisfy in order to be able to decrypt the VM. A key for use in decrypting the VM has previously been sealed into multiple (and preferably into all) computing resources (402) in the network into which the VM is to be provisioned, and has been sealed such that a computing resource can obtain the key only if it is in a state that satisfies the security profile, or at least one security profile, to which the key is bound The VM manager or provisioner (403, 408) creates a VM launch package that includes the encrypted VM and that also includes a key that may be used in decrypting the encrypted VM. When the VM launch package is received at a computing resource (402), the computing resource will not be able to recover the key for use in decrypting the VM—and hence will be unable to decrypt the VM—unless the computing resource satisfies the security requirements indicated by the security profile. The VM manager or provisioner can thus be sure that the VM will not be launched on a computing resource that does not meet the desired security profile. Alternatively the VM manager or provisioner (403, 408) may send a token corresponding to a desired security profile with an encrypted VM. A computing resource uses the token to obtain a key to decrypt the VM but the computing resource will not be able to recover the key unless the computing resource satisfies the security requirements indicated by the token.